A: We started to develop the software in the early 1990's as a component of a specialized integrated engineering software system. In 1995 we decided to make it available as a stand-alone software product, which was originally called Calc95.

Q2: Why have you released a free version of Calc?

A: Because we thought computer users would find it useful. We also hope that once people have used the free version they might consider upgrading to the newer paid version.

Q3: Who are Flow Simulation?

A: Flow Simulation develops software under contract and provides consultancy services for the engineering and financial services industries. See our company web site for more details.

Q4: Who uses Calc?

A: Because of the way Calc is distributed it is difficult to obtain precise numbers of users. On a typical day, between one and two thousand users download Calc from our web site. Calc can also be obtained from magazine cover disks, online software archives, user's home pages and in software collection CD's sold separately or included with textbooks. We currently estimate that about 4 million users have downloaded Calc. Many users report that they have distributed the software around their departments or organizations, which include major industrial corporations and government departments. A large proportion of users are located in North America, although there are registered users in most countries of the world. As well as scientific and engineering industries, Calc is very popular in education, financial services and health-care. For further background you can see a selection of user comments.

Q5: Calc is great. What can I do to help?

A: Please tell all your friends and colleagues about Calc, or give them a copy of the software. It is also very helpful if you mention our software in any newsgroups, mailing lists or on-line forums you participate in. If you subscribe to a journal or newsletter specific to your industry or area of interest, you could bring it to the attention of the editor as a useful free resource.

Q6: What's the difference between the free version of Calc and the paid version?

A: The paid version (available from our Windows order page or Windows Mobile order page) is a later version of the software with more features. In addition, the CD version has many extras which we can't make available for download because of bandwidth considerations (see the CD product page).

Q7: How do I get a copy of the latest (premium) version?

A: You can order the versions for Windows or Pocket PC for immediate download by electronic software distribution from our Windows order page or Windows Mobile order page. You can also order the CD from the CD product page. The CD contains versions for all supported platforms and includes support and a printable manual and many other extras.

Q8: What are Flow Simulation's contact details?

A: Our postal address is: Flow Simulation Ltd., Sheffield Science Park, Arundel Street, SHEFFIELD, S1 2NS, England e-mail: info@flosim.com Web: http://www.flosim.com/. If you e-mail us, please use a meaningful message subject line to ensure that our spam filters don't remove it.

Q9: Is Calc Y2K compliant?

A: In case anyone is still interested, we tested it using the rollover date and other key dates. It worked fine.

Licensing Issues

Q1: How do I register?

A: You can register online using our web form.

Q2: The Web form doesn't work/I don't have access to WWW - how do I register?

A: You can either e-mail us at info@flosim.com or use the form which comes with the Calc documentation and mail it to us at Flow Simulation Ltd., Sheffield Science Park, Arundel Street, SHEFFIELD, S1 2NS, England.

Q3: Why should I register?

A: Our licence terms for the free version allow 90 days of use, after which you need to register to continue legally using the software. Although we have chosen to make Calc free, it still costs us time and effort to develop it, so we don't think it is unreasonable to ask users to register it. You don't need to register if you have purchased the paid version.

Q4: What does registration cost?

A: Registration of Calc is completely free of charge.

Q5: What happens after 90 days?

A: Nothing. Calc does not contain any time-out mechanisms or nag screens. To a large extent we are relying on users' honesty and fairness, and we have tried to make registration as easy as possible.

Q6: Can I really download this program and use it for free for as long as I need it?

A: Yes. But please remember to register.

Q7: Why do you ask for personal information, if the product is free?

A: If we were charging a fee for the software, most users would expect to give their name, address, email etc. along with their credit card details. Your contact information is still important to us, whether or not we charge a fee for using the software. The demographic information and feedback help us do a better job of continuing to develop the product, and allow us to occasionally contact users with news of updates. Without this information it would be much more difficult for us to make Calc a success.

Q8: I'm not giving you my details. What are you going to do about it?

A: We understand that some people are very sensitive about giving their personal details online. We would like to assure you that we respect the confidentiality of information you supply to us, and under no circumstances would we give that information to a third party. You may leave blank any fields you feel particularly strongly about, but please at least give us your name, approximate location and a means of contacting you.

Q9: If I upgrade do I need to register again?

A: No. You only need to register once. If your details have changed it would be helpful if you could let us know; it may be easiest to use the registration form again to do this.

Q10: Can I edit my details online?

A: No. There is no online access to user details once they are entered for security reasons.

Q11: What are the terms for site licensing?

A: Calc registration is free, whether you install it on one computer or a thousand. Please indicate when you register if you are using it site-wide, and please be sure to give the name of the organisation. By registering in this way, you don't need to have every user register individually.

Q12: What will happen to the details I supply when registering?

A: We keep user details for our records. We use this information to better understand the demographics of Calc users, and also to encourage feedback to enable us to improve the product. We might occasionally contact you to let you know of new versions of the software, unless you specifically ask us not to. We do not make the information available to third parties, and treat any information you give us as confidential.

Q13: I have purchased Calc on CD/paid download. Do I still need to register?

A: There is no need to register if you have purchased the latest supported version from us. This version comes under a different licence which can be found on the CD or with the download.

Q14: Can I obtain the source code of Calc?

A: Sorry, no. Calc is not an Open Source project. We have no plans to make Calc Open Source. Note that Calc is not "free" in the sense of the word used by organizations such as the Free Software Foundation. It is licensed software, and the terms of the licence require you to register it. But registration is free.

Q15: Is it okay to include a link to Calc on my personal home page?

A: Yes, please do. More information about how to do this can be found on the Linking to Calc page.

Q16: Is it okay to include a link to Calc from our organization's web site?

A: Yes, please do. More information about how to do this can be found on the Linking to Calc page.

Q17: I would like to redistribute Calc. Is this okay?

A: Yes, please feel free to redistribute the free version of Calc in its original form to friends, colleagues, etc. However, you may not modify the files, separate or distribute them individually, or alter the copyright and legal notices. The people you give the software to should register it if they want to use it after 90 days, but that's not your problem. Of course you must not distribute the purchased versions; if in doubt refer to your licence.

Q18: I would like to unofficially "mirror" Calc on my home page. Is this okay?

A: "Mirroring" refers to the practice of keeping a copy of a file on your web site for visitors to download, instead of going directly to the original site. We have no objection in principle to web site owners doing this. In practice however, this can cause problems when we update the software, because we don't know who has out of date versions of the software on their site. We support a number of "official" mirrors, which simply means that we are aware that they are making the file available and direct users to them, and that they have agreed to post updates when we send them. An alternative to "unofficial" mirrors is for sites to link to our download page (as described on our Linking to Calc page). This helps us to keep downloads up-to-date.

Q19: Do you have a logo for Calc I could use as the link?

A: Yes. You can find one on our Linking to Calc page.

Q20: Can I distribute Calc along with my software product/collection?

A: Please contact us at info@flosim.com if you wish to distribute Calc along with another product or part of a software collection. The answer is likely to be yes, as long as it is made clear to users that Calc is a separate product which is credited to Flow Simulation. You will need take care not to include any wording that gives the impression that Flow Simulation endorses your product. You must not modify the files, separate or distribute them individually, or alter the copyright and legal notices. Users need to register the software with us if they want to use it after 90 days.

Q21: Can we include a customized version of Calc as part of our software?

A: No, sorry. You may not disassemble or reverse engineer or incorporate into another work the software or its components. If you have a commercial requirement for a customised version of the software please contact us to discuss your requirements. We can supply special versions of the software incorporating corporate branding and industry-specific or application-specific calculator functions.

Q22: I am a professional journalist. How do I get a media kit?

A: Please see our on-line media kit, or contact us at info@flosim.com with your mailing address if you need a media kit sending to you.

Q23: I work for a magazine publisher. May we include Calc on our cover CD?

A: We would love to see Calc on your cover CD. Please contact us at info@flosim.com for permission or if you need a written release. Please do not separate the files, distribute them individually, or alter the copyright and legal notices. You can find more resources in our on-line media kit.

Q24: How do I obtain technical support?

A: We are not able to make a commitment to provide technical support for the free distribution version of Calc. However, please feel free to e-mail us at info@flosim.com if you have a problem or query, or suggestions as to how we could improve the product. We will do our best to deal with your request if we can. Alternatively, you can write to us at our address below. We also sell a fully supported version of the software which can be ordered for immediate download from our Windows order page, Windows Mobile order page, or ordered on CD from the CD product page.

Installation

Q1: How do I download and install Calc?

A: You can download Calc from the Calc download page. Select the site you wish to download from by clicking the appropriate link. Your browser will prompt you for a location to save the file. The downloaded file is a self-extracting zip archive. Run it to extract the files into the directory of your choice. For more detailed information, see the online documentation

If you are installing to a Windows CE device (e.g. Pocket PC, H/PC), the installation program should start ActiveSync automatically when the files have been extracted. ActiveSync should then take over and offer to install Calc for you. If this does not happen for some reason, you can also install the software by manually copying the CAB file onto the device. The CAB file can be found in the Calcx directory (where "x" depends on the platform). You can run the CAB file on the device itself (using the File Explorer on the device, and opening it), because Windows CE knows how to install the software from CAB files.

Q2: Why doesn't Calc have a 'proper' Windows install program?

A: The size of the Calc executable is of the order of 500k and the compressed distribution file is not much larger. This makes Calc extremely quick to download and capable of distribution using low capacity media like diskettes. We have looked at several professional install programs and determined that the resulting installation files would be considerably larger than the software itself. We have therefore custom built a lightweight installation program. We think most users would prefer to have the benefit of a smaller download file.

Q3: Will installing Calc unleash some bug that will crash my system?

A: We certainly hope not! Millions of people have installed Calc on their systems without problems.

Q4: Where is the Help file?

A: The help files have their own directory, "CalcHelp". A single index file "index.htm" exists in the Calc directory and links to the other files.

Q5: How do I replace the Windows Calculator with Calc?

A: This depends slightly on which version of Windows you have. Drag and drop a Calc shortcut to your Start Menu (right click on the "Start" button and select "Open" to open it, or right click on the task bar and select "Properties" and selecting the "Start Menu Programs" tab, or go directly to the directory "C:\Windows\Start Menu\Programs\Accessories"). A shortcut to the Windows Calculator should be in the "C:\Windows\Start Menu\Programs\Accessories" directory and can be deleted and replaced with the Calc shortcut. Alternatively, edit the Windows Calculator shortcut and change the target to the Calc executable.

Q6: Another program starts the Windows Calculator. How do I get it to run Calc instead?

A: The executable for the windows calculator is usually called "calc.exe" and can be found in the Windows directory (typically "C:\Windows"). To replace this with Calc, first rename "Calc.exe" to e.g. "Calcexe.old" and then create a shortcut to Calc and rename it "Calc.exe". If for any reason you need to reverse this process, delete the shortcut and rename "Calcexe.old" back to "Calc.exe".

Q7: How do I get the calculator icon to appear on my desktop?

A: Put a shortcut to the executable onto your desktop. First use Explorer to go to C:\Program Files\Calc98 (or wherever you installed Calc). In that directory you should see a file Calc.exe. Select Calc.exe and use the Edit/Copy menu item or Ctrl-C to take a copy. Now go to your desktop and right click on it, and from the menu select "Paste Shortcut". You should then have a shortcut to Calc on your desktop. If you want, you can re-name the shortcut by selecting it and then clicking on the title area. Be careful not to accidentally move the Calc.exe file itself onto your desktop by simply dragging it there, otherwise you will get extra files appearing when you run it.

Q8: Why does my browser window fill with garbage when I try to download factory.prp?

A: In Internet Explorer, right mouse click on the link and select "Save Target As..." from the pop-up menu, and save to the Calc directory. In Netscape Navigator, right mouse click on the link and select "Save Link As..." from the pop-up menu, and save to the Calc directory. If you have navigated to our website using HTML Help this will not work; you have to use an HTML browser such as Internet Explorer or Netscape Navigator.

Q9: Where does Calc store its files?

A: Calc stores its files in the directory from which it is run. On Pocket PC (Windows CE) some files are stored in "My Documents".

Q10: Why does Calc use the Windows Registry?

A: Using the Registry allows different users of the same computer to individually configure and customize Calc.

Q11: What Windows Registry entries does Calc use?

A: Calc saves registry settings in "HKEY_CURRENT_USER/Software/FlowSimulation/Calc". The registry entries are used to store the current calculator mode, display configuration and keypad layout.

Q12: Why are you using HTML Help?

A: We switched from Windows Help (WinHelp - the help system used exclusively on versions of Windows up to Windows95) to HTML Help because this was the direction Microsoft encouraged developers to go at the time. HTML Help offers many advantages over WinHelp, but unfortunately support in older versions of Windows was incomplete. In these cases Calc needs to find a browser to display the help files, which gives rise to other problems (see below).

Q13: Why does Calc try to use Internet Explorer?

A: On older versions of Windows which do not have built-in support for HTML Help, Calc tries to locate an HTML browser. When you click on the Help button, Calc first tries to launch Windows HTML Help (which is a standard component of more recent versions of Windows). If this fails it starts looking for Internet Explorer, because most Windows systems have IE installed. If Windows fails to locate IE it looks for Netscape Navigator. If this fails, the user is given the opportunity to specify the location of the browser. You can also specifically tell Calc which browser executable to use within the Data tab of the Options dialog.

Q14: Why does a file called "default.dat"' keep appearing on my desktop?

A: Calc creates a file called "Default.dat" in the directory from which it is run to save values when you quit the calculator. You can delete the file, but you will get a new one the next time Calc is run. When you install Calc on Windows, one way of making it easily accessible is to drag a shortcut of the Calc executable onto the desktop. The problem occurs as a result of accidentally dragging the executable itself, or a copy, onto the desktop, instead of creating a shortcut. This means that Calc gets run from the directory corresponding to the desktop, and this is where it will store its data file. To create a shortcut, drag the object and hold down the ALT and SHIFT keys before releasing the mouse button. Or you can use the right mouse button as you drag to get a pop-up menu; then select "create shortcut here".

Q15: Why does a file called "default.dat"' keep appearing in my Start Menu?

A: Calc creates a file called "Default.dat" in the directory from which it is run to save values when you quit the calculator. You can delete the file, but you will get a new one the next time Calc is run. When you install Calc on Windows, one way of making it easily accessible is to drag a shortcut of the Calc executable onto the Start Menu, for example using the Taskbar Properties or adding it to the "C:\Windows\Start Menu\Programs" folder. The problem occurs as a result of accidentally dragging the executable itself, or a copy, onto the Start Menu, instead of creating a shortcut. This means that Calc gets run from the Start Menu folder itself, and this is where it will store its data file. To create a shortcut, drag the object and hold down the ALT and SHIFT keys before releasing the mouse button. Or you can use the right mouse button as you drag to get a pop-up menu; then select "create shortcut here".

Q16: How do I get back to the installation prompt to add a shortcut?

A: You can run the installation program at any time by double clicking on SETUP.EXE in the Calc directory. This program only installs shortcuts, it does not fully re-install the software. Nor does it delete shortcuts that already exist.

Q17: I have just upgraded Calc. Why does it look and behave like the old version?

A: You may have had Calc running when you ran the installation program. You need to make sure that Calc is not running, and then run the installation again.

Q18: Why does it try to extract the files every time I try to run it?

A: You are probably trying to run the self-extracting zip file instead of the Calc executable. This can sometimes happen if you create a shortcut to the zip file which gets run instead of the extracted file. The zip file will be called something like c9853w.exe. You run this once to create an installation directory ("/Program Files/Calc" by default). This directory contains a file Calc.exe which is the program.

Q19: How do I un-install Calc?

A: Please see the section below for problems related to Windows or Windows CE versions, as appropriate.

Q20: How do I install Calc on Windows Vista?

A: In order to run the installer program (Calc9853w.exe, etc.) you will need to right-click on the file and select "Run as administrator". If you do not do this, Windows will not be able to save the unpacked files to the default directory, and you will get the error "Can't create output file C:\Program Files\Calc98\CALC.EXE" or similar. Next you should see a prompt to either Allow or Cancel. You should click on Allow in this case because you know you have intentionally run a program as administrator. Now you can click on the Unzip button as normal and the files will be extracted and the setup program will run to install the software.

Software Development and Availability

Q1: How frequently is Calc updated?

A: It largely depends how busy we are. Our main business activities obviously take priority. The period between major releases is typically two years.

Q2: Which Windows operating systems does Calc run on?

A: Calc runs on Windows 95, Windows 98, Windows ME, Windows NT, Windows 2000, Windows XP and Windows CE.

Q3: Is there a version of Calc for Windows CE (Pocket PC)?

A: Yes. You can get it from the usual download page.

Q4: Is there a version of Calc for the Casio BE-300?

A: Yes. You need to download the special version for the Casio BE-300/500 Pocket Manager.

Q5: Is there a version of Calc for 16 bit Windows (e.g. Windows 3.1)?

A: There is a 16-bit version of Calc95. This version has not been developed further to keep up with Calc, but can still be downloaded for use on 16-bit systems.

Q6: Is there a version of Calc for Linux?

A: No, there is no native version for Linux. However we have verified that it works under Wine. If you want to use it under Wine we suggest you extract the Calc executable from the zip file and run that directly using Wine, rather than trying to run the installer which may not work. The zip file may have the extension .exe if it is self-extracting. You can extract the files using unzip from the shell.

Q7: Is there a version of Calc for Unix, BSD etc.?

A: Sorry, no.

Q8: Is there a version of Calc for Palm?

A: Sorry, no.

Q9: Is there a version of Calc for Psion (EPOC)?

A: Sorry, no.

Q10: Is there a version of Calc for Apple Macintosh?

A: Sorry, no. Unfortunately we do not have the resources to develop a parallel version of the software for the Apple Macintosh.

Q11: Can I install Calc on a WindowsCE device connected to an Apple Macintosh?

A: Yes. You will need to unpack the download file manually, because the self-extracting zip file only runs on Windows. If you change the filename extension from .exe to .zip, the Macintosh should recognise it as a zip file which you can then open. You then need to transfer the .cab file to the device, and then run the .cab file on the device to install the software.

Q12: What happened to the extra fonts in Calc95, e.g. Buttons, Sevenseg and Minitron?

A: We now support arbitrary font sizes and that means we need to use TrueType fonts. Buttons, Minitron and Sevenseg fonts supplied with Calc95 weren't TrueType so you could not re-size them. It seems that these fonts were quite popular and we plan to re-introduce them as TrueType fonts in a future version.

Q13: Why is Calc limited in exponent to 1e300 and 15 digits precision?

A: Calc is written using the programming language C++ and using the Microsoft Visual C++ development system and runtime support, which includes a mathematics library with various floating point variable types. We use the data type with the greatest precision on 32 bit systems, which has a maximum (base 10) exponent of 308 and a little over 15 digits of precision in the mantissa. This is not dependent on the operating system, nor is it dependent on the floating point hardware (provided performance is not an issue). We could use a special high precision maths library, or write our own, to get arbitrarily high levels of precision. But the applications of higher precision mathematics are fairly specialised and we did not think it justified the programming effort or performance penalty in a general purpose scientific and engineering tool like Calc.

Solutions to Common Problems running Calc

Q1: Can I get rid of the Flow Simulation splash screen when Calc starts?

A: Please do not attempt to remove the Flow Simulation splash screen. Calc is not idle while the splash screen is displayed, but is actually loading the physical properties and constants, so there would still be a delay even if the splash screen were removed.

Q2: Why can't I use the computer keyboard instead of clicking with the mouse on the buttons?

A: Use the keyboard shortcuts. The keyboard shortcut keys are listed in the documentation ordered by key and function.

Q3: Could you please provide a list of the keyboard shortcuts?

A: The keyboard shortcut keys are listed in the documentation ordered by key and function.

Q4: How do I make the button legends bigger?

A: Click on the "opt" button or Options menu to bring up the Mode dialog box. Select the "View" tab and click on either the "Main Keys" or "Function Keys" buttons to change the button size, spacing, font etc. For more information, see the documentation.

Q5: How do I make the display bigger?

A: Click on the "opt" button or Options menu to bring up the Options dialog box. Select the "Display" tab to change the font, size, background colour etc. For more information, see the documentation.

Q6: Where are Calc's statistics functions?

A: Click on the "opt" button or Options menu and select statistics mode. See the online documentation.

Q7: Where are Calc's financial functions?

A: Click on the "opt" button or Options menu and select financial mode. See the online documentation.

Q8: Where is the pi button?

A: Use the shift button to get additional functions in normal operation. See the online documentation.

Q9: Where is the percent button?

A: Use the shift button to get additional functions in normal operation. See the online documentation.

Q10: How do you get mode selections to be the default mode?

A: Calc saves its settings in the Windows Registry automatically when it exits.

Q11: How do you get the button size to stay at a given size?

A: Calc saves its settings in the Windows Registry automatically when it exits.

Q12: How do I view the stack in RPN mode?

A: For version 5.3, click on the "shift" button, and then the "stack" button, or use the keyboard shortcut (Ctrl-^). For version 5.6 and later you need to enable the stack in the Options/Display dialog.

Q13: Where is the button to exchange X and Y in RPN mode?

A: For versions up to 5.3, you need to click on the "shift" button, and then the "x><y" button. On these versions to get the number into the X register you need to do an "Enter" (this is not quite the same as on HP calculators). So the sequence is:
2 Enter 3 Enter X><Y divide, result 1.5 (not 0.6666667).

Q14: Why, after using for a while in RPN mode, do I get a stack full message?

A: In RPN it is possible to keep pushing values onto the stack which for one reason or another never get popped off again. Although the stack is quite deep (16 levels) it will tend to fill up over time if this keeps happening and the calculator is not cleared periodically. This results in the error message when you try to push more values onto the stack. Hewlett Packard calculators simply discard values off the end of the stack when this happens, and some people expect this behaviour. Versions from 5.6 onwards behave more like the HP calculators. In the meantime it is suggested that the stack is periodically cleared, e.g. when starting a new calculation, to avoid the stack gradually filling up over time. This problem does not affect versions 5.6 onward.

Q15: Where is the button to move the stack down in RPN mode?

A: On version 5.3 you need to click on the "shift" button, and then the "R<" (stack roll down) button.

Q16: Why do the trigonometric functions give inaccurate values (e.g. sine of 10 degrees gives -0.5440211109)?

A: You have the angle mode set to Radians, instead of degrees. Click on the "opt" button and select the "Mode" tab or use the Options/General menu, and select "deg" as the angle mode. The correct answer for the sine of 10 degrees is 0.1736481777 .

Q17: Why do the trigonometric functions give inaccurate values (e.g. sine of 10 degrees gives 0.156434465)?

A: You have the angle mode set to Gradients, instead of degrees. Click on the "opt" button and select the "Mode" tab or use the Options/General menu, and select "deg" as the angle mode. The correct answer for the sine of 10 degrees is 0.1736481777.

Q18: How do I clear the Memory?

A: To clear the memory, clear the calculator using the "AC" button (or just clear the display using the "C" button), then click on "M_in"

Q19: Is there a way to get Calc to put the decimal point in automatically (like an adding machine)?

A: No. Whilst this can work well for an adding machine as used for book-keeping, it would be very confusing for a general purpose calculator. A simple solution is to simply work in pence, rather than dollars or pounds. The danger with this is that you forget to enter the zeroes for the pennies when entering a round number of pounds or dollars, especially if you do not use calculators exclusively in this way.

Q20: How do you change the decimal point symbol?

A: Click on the "opt" button or Options menu and select the "Display" tab/submenu. You can then change the decimal symbol. When you install for the first time it should default to the regional setting on your computer.

Q21: How do you change the thousands separator?

A: Click on the "opt" button or Options menu and select the "Display" tab/submenu. You can then change the digit group symbol, or disable it (by setting to "no").

Q22: Why, if I enter "1 + 2 x 3 =" do I get 7 and not 9?

A: The order in which arithmetic operations is carried out is called precedence. Calc defaults to algebraic precedence which is the way most scientific calculators work. This means that multiplication takes precedence over addition, which is equivalent to 1 + (2x3) = 7 because the multiplication is evaluated first, even though it was the second arithmetic operation entered . Some calculators (particularly very simple ones) do not use algebraic precedence and only the order of entry is significant, so (1 + 2) x 3 = 9. Calc can be configured to use either type of precedence by clicking the Mode button and selecting the Mode tab. There is a section on this tab page called "Precedence" which gives you three options: As Entered, Algebraic (the default) and a third option "RPN" (Reverse Polish Notation; a very elegant solution which allows you to enter complex expressions without using parentheses, and made popular by Hewlett Packard's calculators). If you switch to "As Entered" mode, the calculator will compute "1 + 2 x 3" as 9.

Q23: Why is the value truncated to two significant figures when I try to calculate a monthly interest rate?

A: When you switch to financial mode, the display automatically switches to Finance mode (i.e. two decimal places). This means that if you calculate a monthly interest rate (which is likely to be some fraction of one percent) there is not sufficient accuracy unless you flip back to decimal mode. To change to monthly interest rate, use the buttons on the rates dialog which converts without losing accuracy. From version 5.6 onwards the rate for monthly interest and other periods is computed automatically when the appropriate settings are made in the Rate dialog box.

Q24: Why does Calc minimize after a period of inactivity?

A: This is usually because the "auto power off" feature is enabled. See the online documentation.

Q25: Why do I get a message "Unable to open properties database" when I start Calc?

A: For some reason Calc could not load the properties and constants data. These are stored in files in your installation directory with the extension .PRP. Calc looks for a file called DEFAULT.PRP in this directory, which is where you would store customized properties and constants data for automatic loading. If this file is not found, the file FACTORY.PRP is loaded from the same directory. If both files are missing or inaccessible for some reason, Calc fails to load the data and the properties and constants will not be available. Check if these files have been deleted or moved. If no properties files can be found, they can be replaced from your backup copies of the distribution files, or you can re-run the Calc setup.

Q26: Why do the HEX input keyboard shortcuts A-F only work with the keyboard shift?

A: Some of the lower case letters a-f are already used for other functions.

Q27: Why do I get incorrect results after performing division in HEX mode (or other integer mode)?

A: If you perform a division in HEX or other integer mode the fractional part of the calculation is retained, although it is not visible. If you switch back to Decimal mode you can see the full precision of the result of the division. The hidden fractional digits sometimes account for an unexpected result on a subsequent multiplication, for example. Versions 5.6 and later of Calc have an "Int" function which can be used to truncate the fractional part. With earlier versions of Calc you can achieve the same effect by the "trick" of using Copy then Paste to re-enter the value as a string which has the effect of removing the fractional part.

Q28: Why do am I getting the message "No Data" in the display?

A: Sometimes this happens if the data file has somehow become corrupted. Delete the file "default.dat" which should be in the Calc98 directory. On Windows CE devices it may be in the "My Documents" folder.

Q29: How do you input times in hr/min/sec?

A: Use the sexagesimal input button as follows:

After entering the number of hours (if any) click on the "hr" button. The "hr" button legens changes to "min". Enter the number of minutes, and click the "min" button, which now changes to "sec". Enter the number of seconds. From version 5.6 onwards use the ":" button for each input.

Example (version 5.3): to enter a value of 2 hr 55 min 40 sec

select Time mode. 
clear calculator.
enter 2
click "hr" (2nd button, 3rd row on function keypad - changes to "min").
enter 55, then "min" ("hr" button legend has changed).
enter 40, then "sec"
click "=" : result 02:55:40.00

To use the keyboard, enter the number of hours, then use the "h" key instead of the "hr" button. Enter the number of minutes. Now it gets a bit less intuitive, because the "hr" button on the keypad on the screen changes to "min", but you still use the "h" key. Now enter the seconds, if any, followed by "h" again, then the enter key for equals.

The sequence is: "2h55h40h(return)". Any leading zeroes and the final "h" can be omitted.

For version 5.6 use the ":" button or key instead of hr/min/sec or the "h" key.

Q30: Why am I getting odd fractions denominators in feet/in mode?

A: Check that you have not set the maximum denominator to a value less than 64 in the Options/Display dialog. Values lower than 64 will take precedence over the default value of 64 for this mode.

Q31: Why don't the depreciation functions work as shown in the manual?

A: There is a bug in some versions of the documentation (version 5.6) - you need to perform the depreciation function first, then multiply by the capital cost less any residual value. E.g.: 10 SLD 5 = X (10000 - 1000) = This only applies to algebraic mode - the RPN example is correct.

Solutions to Common Problems running with Windows

Q1: When I click on Help in the calculator, why is the page not found?

A: This sometimes happens when the calculator executable file is moved, for example to the taskbar, instead of using a shortcut. If it doesn't run the executable from its own directory, it can't always find files such as help and other support files. On Windows, the SETUP.EXE program in the Calc directory can be used to add shortcuts.

Q2: Why does my computer freeze up when I am running Calc (or other program)?

A: There are many possible causes of this including device driver problems, damaged registry, faulty RAM or cache or other hardware problems, damaged Windows system files or DLL files, viruses and of course an error in the program itself. Given that Calc has run without difficulty on over a million computers it is most likely that there is some problem specific to your machine. If the program "freezes" or "hangs" you can close it using Ctrl-Alt-Del to bring up the task manager. This will then allow you to find any programs which are shown as "not responding" and close them. They may disappear immediately or there may be a delay of up to thirty seconds before a second confirmation dialog box appears. Often when this happens Windows will continue to be unstable and eventually the task manager itself freezes, or a fatal error occurs (see below). For this reason we recommend making sure that you save all data in any running applications if the system starts to behave in this way. If the problem persists, use the troubleshooting checklist below.

Q3: Why does my computer keep crashing with a Fatal Exception error (blue screen)

A: These are usually Fatal Exception 0D (General Protection Fault) and Fatal Exception 0E (Page Fault) and are caused by the hardware detecting an attempt by a program to access memory outside its permitted address space. There are many possible causes of this including device driver problems, damaged registry, faulty RAM or cache or other hardware problems, damaged Windows system files or DLL files, viruses and of course an error in the program itself. Given that Calc has run without difficulty on over a million computers it is most likely that there is some problem specific to your machine. Usually the problems are not restricted to a single application and may occur apparently randomly. You can learn more about Fatal Exceptions at the Microsoft web site. We suggest you follow the troubleshooting steps below, checking to see if the application works after each step.

Q4: Why am I getting the message Exception: 0xC0000005?

A: Exception: 0xC0000005 indicates an access violation, in other words the program tried to read or write memory it wasn't supposed to. The details of the actual memory address aren't very helpful. An access violation can be caused by a programming error. But it can also be the result of a hardware error or faulty memory, or the actual error may have occurred in a DLL or other system file. The executable file for Calc could also have been corrupted. But note that unless the file you originally downloaded fails to self-extract, it is very unlikely that the download itself is corrupted. A corrupted data file (default.dat) can also occasionally cause problems. We suggest you try the following in turn, until Calc runs without problems:

Reboot your PC (after closing all programs)
Delete the "default.dat" file in the Calc folder
Delete the "default.dat" and reset to factory settings by clicking Options/Data/Factory Settings button and closing (see above close procedure)
Remove the Calc directory and run the original download file to unpack the files and re-install Calc
Repeat the step above with a freshly downloaded copy of the software from our web site.

Q5: How can I get rid of Windows crashes, hangs and freeze-ups?

A: This is usually not a problem with Calc, but can have a variety of causes. Unfortunately, there is no easy answer to this. The problems are partly due to the diversity of hardware and software used in a typical PC, and also the many constraints, such as backwards compatibility, placed on the designers of the operation system. We suggest the following sequence of troubleshooting checks, running Calc to see if the problem is resolved:

Note down the error message
Reboot your computer (if necessary by switching it off)
Remove Calc as described above and re-install it from the file you downloaded (if the files can be extracted it is very unlikely that there is a problem with the downloaded file)
Temporarily disable any running Virus Scanners
Check that you have plenty of disk space - run Disk Cleanup if required
Check the available system resources (right mouse click on My Computer, Properties tab)
Run Scandisk (could be an error on the disk)
Try rebooting in Safe Mode (Windows 95 - hold down F8 key while rebooting, Windows 98 and later - CTRL key)
Perform a clean boot of your computer using msconfig utility (Windows 98 onwards)
Check the Microsoft knowledge base for the specific error
Check that motherboard and video drivers are up-to-date
If possible, physically swap out memory modules to check for faulty memory chips
Disable any external cache in BIOS utility
Re-install Windows (backup your data first)
As a last resort, reformat the hard disk and re-install Windows (experts only - backup your data and make notes of settings)

Q6: Why do I only get the digits before the decimal symbol of the number when I try to paste into Calc from another application?

A: If you are getting this problem and you are using version 5.30 and you are using a character for the decimal separator other than the period (e.g. the comma symbol) then the decimal separator will not be parsed correctly. This problem is fixed in later versions.

Q7: Why do I only get the first digit of the number when I try to paste into another application?

A: There is a bug which affects the Unicode version of Calc version 5.3 only. The suggested work-around is to use the non-Unicode version. You only need to run the Unicode version if you are running WindowsNT, 2000 or XP and you are using a non-Latin-1 codepage (e.g. Hebrew, Arabic or Eastern European). The bug is fixed in the version 5.6.

Q8: Why do I sometimes get a Windows error after starting in RPN mode?

A: There is a bug which affects Calc version 5.3 on Windows only, when used in RPN mode. If you have values on the stack, close the application and then start it again and immediately use a unary operator (e.g. 1/x) you may get a Windows error. The suggested work-around is to run Calc as a tool tray application (select Options, View tab, Taskbar Tray Icon). This means that after closing Calc it is actually minimised to the tool tray so it does not need to start again next time you use it. The bug is fixed in version 5.6.

Q9: How do I un-install Calc?

A: You can uninstall Calc using the setup.exe application in the installation directory ("/Program Files/Calc" by default). There should also be a link called "uninstall". You can also use the Windows Control Panel and select Add/Remove Programs. You should then be able to select Calc from the list to run the uninstaller.

If you have obtained Calc from an archive which has an older version of the installer, there may not be an automated uninstall option. In this case, simply delete the directory into which you installed Calc (which is usually "/Program Files/Calc"). There is a very small amount of data in the registry, and if you really want to delete it, then first run the calculator and select the Data page of the Options dialog and click on the "Factory Setting" button. Click the "Yes" button in the confirmation message, then quit the application. You can then delete the files as described above. If you created any shortcuts to Calc (e.g. on the desktop or Start Menu), you will need to remove these also.

Q10: How do I stop Calc from starting up every time I start the computer?

A: If you configured Calc to start up automatically and now wish to disable this, you can run the setup program again (setup.exe in the Calc directory) and disable it. Alternatively you can manually delete the shortcut from the Startup directory. You can reach the Startup directory by right clicking on the Start button and selecting Open, then go into Programs and then Startup.

Q11: Why does Calc sometimes hang, e.g. when I click on the '=' key?

A: A possible cause of problems is if you have a Logitech QuickCam installed. The webcam driver software, and in particular LVPrcInj.dll, attaches itself to other software running on your computer and can cause problems with other applications. A suggested workaround is to go to C:\Program Files\Common Files\Logitech\LVMVFM\ (or use the search feature to find the location of the file) and rename the file LVPrcInj.dll to LVPrcInj.old to prevent it from loading. It may be necessary to reboot the computer in Safe Mode to rename the file if it is in use. After renaming the file and rebooting the affected applications should work again, although some "Video Effects" features of the webcam may be disabled. If this fixes the problem it indicates that this driver is the cause, and it might be worth checking the Logitech website to see if they have an updated driver that fixes the problem.

Q12: Why does Calc look funny on Windows Vista?

A: When Calc 5.6 first starts on Windows Vista the menu may run onto two lines (depending on version) and the buttons may be bunched to one side and up against the calculator display. You can correct this by dragging the resize border on the right to make it slightly wider, and possibly extend the border slightly downwards to make the display larger. If you close Calc and restart it the changes should persist.

Solutions to Common Problems running with Windows CE (Pocket PC)

Q1: Why do I only get a very limited set of units conversions on Windows CE?

A: For some reason Calc could not load the properties and constants data from the factory.prp file. Calc has a limited built-in set of conversions, even if the file is not loaded. This is in order to allow quick start-up and to save filestore on Windows CE devices with limited resources. Normally you would want to load the full set contained in factory.prp.
In Version 5.3 the name of the directory for factory.prp is hard-coded. This can give problems on systems where the "Program Files" directory has a non-English name (e.g. "Programme" in German, "Archivos de programa" in Spanish). In this case our recommended work-around is to create a new top-level directory using ActiveSync File Explorer called "Program Files" and create a sub-directory called "Calc98CE". The factory.prp file can then be moved from the original Calc98CE directory to this new one, so that Calc will be able to find it.

Q2: Why can't I save new units and properties on Windows CE?

A: There is a bug in Version 5.3 on Windows CE which causes it to fail to pick up a change to an input field unless you click on another field before clicking the OK button. For example, if you update a conversion factor you need to click on another control such as the units selection box before clicking on the OK button, otherwise the change is lost.

Q3: How do you change the interest rates on Windows CE/Pocket PC?

A: The input boxes are modified using the input panel which is usually visible in the bottom right corner of the display. This is the same way you input diary appointments, use the note taker, etc. On version 5.6 onwards the input panel should be automatically activated when it is needed.

Q4: Why does the input panel sometimes disappear on Pocket PC?

A: There is a bug in Version 5.3 where the input panel is not always made visible after switching from the Today page (or any application which does not show the input panel). A workaround is to switch first to a task which does show the input panel, which in practice means almost any application other than Today, e.g. Calendar.

Q5: How can I close Calc?

A: You can use the task manager, which depends on your device. It is not always particularly easy - the design of Pocket PC is for applications to run continuously until shut down automatically by the system. Some devices come with a task manager built in, e.g. the "Q" button on the iPaq. On Pocket PC you can go to the Start menu, select Settings, then the System tab, then select the Memory icon, then the Running Programs tab, and then select the program and click the Stop button. On the older Palm PC it is Start Menu/Settings/System/Task Manager tab. On HPC you just need to press Crtl-Alt-Del and this brings up the task manager. From version 5.6 onwards you can also use Ctrl-Q to close Calc,. On HPC devices, when using version 5.6, the window close button closes the application.

Q6: Why is there no Close button or menu item on Pocket PC?

A: Microsoft's design guidelines and "Designed for Pocket PC" logo requirement for Pocket PC state that user must not be able to close the application themselves and that there is no Close "X" button or a File->Exit menu. This is because by design the programs keep running until the device runs out of resources and applications are then shut down automatically. This saves the user from having to manage applications. It is a nice idea but caused a lot of controversy since most Pocket PC users are also Windows users and expect to be able to close their programs. Microsoft seem to have had a change of heart with the introduction of Pocket PC 2002, although the re-introduced close button usually only hides the application. The close button is still permissible in H/PC but was removed for this platform as well by mistake in version 5.3 but works again from version 5.6 onwards.

Q7: How do I get rid of Calc from the Start menu?

A: Use the ActiveSync explorer and go to "My Device/Windows/Start Menu/" then delete the Calc link. You can also do this using File Explorer on the device. Check Settings/Menus - there should only be one Calc98 item. If necessary, uncheck it so that it only appears in Programs and not on the Start Menu. These steps are necessary because of a bug in the current version of Calc98 installer when used with Pocket PC 2002.

Q8: How do I get rid of the second Calc icon in Programs on Windows Mobile 2003?

A: You can remove the second icon by going to Programs > File Explorer. Now navigate to My Device/Windows/Start Menu/Programs, and you can delete the second icon. If you don't have File Explorer on your devices, you can remove the icon using the Explorer from ActiveSync by navigating to My Pocket PC\Windows\Start Menu\Programs and deleting the icon. The second icon appears because of a change in PPC2003 - the software was developed before the new version of PPC was available. Version 5.6 fixes this problem.

Q9: Why do the menu captions go funny on Pocket PC 2002?

A: There is a bug in Calc Version 5.3 which causes this problem on Pocket PC 2002. This version was developed before Pocket PC 2002 was available - the problem is fixed in version 5.6.

Q10: Why do I get strange characters for the divide and multiply buttons?

A: There is an issue with non-Latin1 character sets (e.g. Hebrew, Greek, Eastern Europe) which causes this problem on localized version of Windows CE. We hope to fix this in the next version.

Q11: Why do I get "No Display Data" in the display?

A: This can happen if the default.dat file has become corrupted for some reason. First shut down Calc (either using task manager or using the close procedure described above). You will then need to delete the file default.dat, which should be in your "My Documents" folder. Calc should then work correctly when it is run.

Q12: Why am I getting the message Exception: 0xC0000005?

A: This can have a variety of causes and may not be a problem with Calc. Exception: 0xC0000005 indicates an access violation, in other words the program tried to read or write memory it wasn't supposed to. The details of the actual memory address aren't very helpful. An access violation can be caused by a programming error. But it can also be the result of a hardware error or faulty memory, or the actual error may have occurred in a DLL or other system file. The executable file for Calc could also have been corrupted. But note that unless the file you originally downloaded fails to self-extract, it is very unlikely that the download itself is corrupted. A corrupted data file (default.dat) can also occasionally cause problems. We suggest you try the following in turn, until Calc runs without problems:

Do a soft reset according to the manufacturers instructions (after closing all programs)
Delete the "default.dat" file in the "My Documents" folder (using ActiveSync explorer)
Delete the "default.dat" and reset to factory settings by clicking Options/Data/Factory Settings button and closing (see above close procedure)
Delete the "default.dat" and then uninstall and remove in ActiveSync
Run the original download file to unpack the files and re-install Calc
If possible verify that Calc installs on another device of the same type
As a last resort do a hard reset of the device according to the manufacturers instructions (after backing up all your data on the device)
Take the device back to the retailer or manufacturer for repair or replacement

Q13: How do I un-install Calc?

A: You can uninstall Calc using ActiveSync from your PC. This also gives you the option to delete the installation files stored on your PC. You can also delete the application on the device by selecting Settings from the Start menu, choosing the System tab, and clicking on "Remove Programs". You will then be able to select Calc from the list and remove it.

Some versions of Calc create a data file (default.dat) which on some Windows CE devices (e.g. Pocket PC) may appear in the "My Documents" folder. You may need to delete this manually to completely remove all trace of Calc. This is not necessary with version 5.6 onwards.

Q14: I pressed the "cnv>" button - why I can't close Calc?

A: There is a bug in the way the "No Units Selected" warning is displayed when you click on the "cnv>" button with no units selected. If you don't dismiss and instead click on another calculator function it is possible for this dialog to hang around in the background. Then every time you click the close button it pops up briefly and brings Calc to the foreground again. You can get rid of it by clicking on Today on the Start Menu which then allows you to get rid of the dialog.

Q15: Why does my Pocket PC freeze up when I try to close Calc using Battery Pack 2003?

A: As far as we can tell there is a bug in Battery Pack 2003 version 5.1.1 such that when you close Calc by tap and hold on the "X" button or using the "X" button in the droplist of running applications, the command bar stops responding. Since you can no longer switch tasks or start applications you have to reset the device in order to continue. This problem also affects other applications as well as Calc. Versions 5.65 and later of Calc have a modification so that it is no longer affected by this problem.

Q16: Why does version 5.6 not work on the HP-720?

A: Unfortunately there is a built-in library on Pocket PC devices which is missing on the HPC 2000 devices, and which Calc requires. There is an updated version 5.67 of Calc for HPC devices available which solves this problem.

Q17: How do I switch on the sound at the end of a countdown in Time mode?

A: Go to Start/Settings/Personal/Sounds & Notifications and make sure that sounds are enabled for "Events". It may be necessary to disable and then enable it to get it working.

Q18: How can I run Calc 5.3 on a square display device such as the HP 6515?

A: The best solution is to use version 5.67 of Calc which has full support for square format Pocket PC devices. However it is possible to use the free Calc 5.3 on these devices with a bit of extra configuration, although without the menu, by following these steps:

Install the software as normal (ignore warning about 'built for earlier version etc.')
Run Calc from Start/Programs
The menu is not visible, so use the keyboard shortcut Ctrl-M to bring up the mode menu (either using the soft keyboard or physical keyboard if you have one).
In the Mode dialog select the View tab and click on the Main Keypad button.
Change Height to 16 and Vspace to 1, then OK.
In the Mode dialog select the View tab and click on the Function Keypad button.
Change Height to 13 and Vspace to 1.
Click on the Font button and change the font size to 10.
Keep clicking on OK until you get back to the calculator which should now be useable.

Q19: In version 5.67 why doesn't help work?

A: The help file should be accessible by selecting the Help option from the Start menu while Calc is actually running in the foreground. If you open help from the Today page and then select the Calc98 link it doesn't work correctly.

Q20: I installed Calc but later my PDA [died/hard reset/was lost]. How do I install it again?

A: If you go to the computer which you used to install Calc on your PDA it should still be there. If you use the Tools/Add/Remove Programs menu option in ActiveSync it will probably still be listed and you can re-install it. Failing that, there should be a directory C:\\Program Files\Calc98a (assuming you used the default location originally) which contains the software, and from here you can run the setup program to re-install. Failing that, if you still have the file you originally downloaded you can simply run this again on a PC linked to the PDA to repeat the installation process.

Q21: Can Calc run on Windows Mobile 2003 SE or later devices supporting landscape mode?

A: The free version 5.3 for ARM should run fine on Windows Mobile 2003 SE and Windows Mobile 5 devices. The only potential problem is the support for landscape, so you may need to have the device in portrait mode when you install it and start the application, as the software was developed before landscape mode was available. If you have accidentally started Calc while in landscape mode you may need to make sure it has 'really' closed before starting it again while the device is in portrait mode. You can make sure Calc exits, as opposed to just switching to the background, by using Ctrl-Q on the soft keyboard, or real keyboard if you have one. Version 5.6 (paid version) in addition to a number of extra features, now has full support for square mode devices and orientation switching, and we would recommend it to take full advantage of higher-end devices like the iPaq 4700 and later. There are more details on the Windows Mobile order page.

Reporting Problems

Q1: How do I get units and conversion factors added to Calc?

A: You can edit the values stored by your own copy of Calc as described in the online documentation. You can help us improve the range of units covered by submitting units for inclusion in the units/properties database. You can do this by e-mail (info@flosim.com) .

Q2: How do I get physical constants or physical properties added to Calc?

A: You can edit the values stored by your own copy of Calc as described in the online documentation. You can help us improve the range of constants included by submitting constants and properties for inclusion in the units/properties database. You can do this by e-mail (info@flosim.com) .

Q3: How do I correct erroneous values for conversion factors or constants?

A: You can edit the values stored by your own copy of Calc as described in the online documentation. If you think that one of the values is in error, please help us by submitting an update. You can do this by e-mail (info@flosim.com) .

Q4: How do I report a bug in Calc?

A: See the bug report page. Alternatively, e-mail us at info@flosim.com.

Q5: How can I suggest an enhancement to Calc?

A: If you have suggestions for future enhancements, please either mention these on your registration form, or e-mail us at info@flosim.com with your ideas. We are very keen to hear user's suggestions. Even if the idea is not new to us, it helps us to know which proposed features are of most importance to users. A large number of the improvements to the last version were as a result of user suggestions.

Q6: I emailed with a request for help; why didn't you reply?

A: We never intentionally ignore messages. Occasionally a message slips through the cracks no doubt, due to human error. But likely possibility is that you or your email hosting provider is using one of several email "Blacklists". These are run by anti-spam enthusiasts and sometimes they get carried away to the point of blocking entire ISPs. In one case BT Internet, one of the largest ISPs, was blacklisted affecting all their users. In our experience these spam vigilantes are unsympathetic to innocent users who are affected in this way, and there is a good description of the problem at http://www.paulgraham.com/spamhausblacklist.html. The usual scenario is that having written a reply we have the frustration of seeing our message rejected, and with no way of contacting the correspondent even to tell them that they are blocking our emails!

Q7: Why did I get this weird email from you?

A: Because we have a prominent website our email address tends to get "harvested" for lists of addresses that spammers use to forge the 'from' address in their spam emails. Because of the way email works it is very easy for the sender of an email to put any arbitrary email address in the 'from' field. For example a spammer or virus writer might wish to make an email appear to come from a reputable company. Unfortunately there is nothing practical we or any other organization can do to prevent spammers forging our email addresses in this way.

Miscellaneous Questions

Q1: Why am I getting 743559489.4000000059 instead of 743559489.4?

A: This problem should be solved in the current release of Calc (version 5).

Q2: Why do you get (e.g.) 12.3499999999999943 if the display precision is set to 16 digits, but 12.35 for 12 digits?

A: Although it is possible to set the accuracy to 16 digits on older versions of Calc, the floating point unit does not support this precision. In the current version of Calc the maximum precision is 15 digits, and most of the rounding problems have been resolved.

Q3: If I put in 19.4, it changes that to 19.3999999999999985. Why?

A: This can happen with older versions of Calc if you set precision to 16 decimals in fixed point mode. In the current version of Calc the maximum precision is 15 digits, and most of the rounding problems have been resolved.

Q4: Is Calc capable of doing fractions?

A: Fraction mode is available in version 5.6 onwards.

Q5: Why don't you have a scrolling tape?

A: This is the most requested enhancement for Calc. We have so far hesitated to add this feature because it is difficult to reconcile, from a usability point of view, with a scientific calculator with matrix functions. We hope very much to find a solution to this and add this feature to Calc at some future date.

Q6: Can Calc calculate exchange rates?

A: If you know the current exchange rate you can of course do the conversion just like any other calculator. It is not so easy to simply add exchange rates to Calc's data files, however, because obviously exchange rates are constantly fluctuating (with the exception of periodically fixed exchange rates such as certain European currencies which are linked to the Euro). The exchange rates built into the properties database are those prevailing at the date indicated.

Q7: How do I bring up the Periodic Table of Elements?

A: In version 5.3 you need to click on the "cnst" button to bring up the constants dialog. Then click on the "Elements" button. From version 5.6 onwards it is accessible from the "Tools" menu.

Q8: How would I calculate a percentage of change?

A: Example 1: In 2004 you have an investment worth $237 and in 2005 you it is worth $376.
Solution: 376 - 237 = / 237 % ('%' key otained by using shift button). Result: 58.65%

Example 2: In 2004 you have an investment worth $237 and in 2005 you it is worth $182.
Solution: 182 - 237 = / 237 % Result: -23.21%

The extra '=' is required to make sure the subtraction is completed before the division.

Q9: Why is a Calc's keypad upside down when compared with a telephone keypad?

The bottom row of Calc's keypad is numbered 123 with 456 and 789 above, like all calculators. A telephone keypad has 123 at the top with 456 below and 789 below that. In both cases the zero and other buttons are on the bottom row.

In around 1960 the telephone companies apparently arrived at their keypad layout as a result of useability research. It probably also made more sense to run the numbers top to bottom because of the alphabetic groups (1=ABC, 2=DEF, etc.) which would suggest reading left to right and top to bottom.

The early mechanical adding machines had a set of number buttons for each digit, e.g. the comptometer, and these ran from 0 (if used) or 1 at the bottom to 9 at the top. This was probably easiest for the design of the adding mechanism. When the first "ten key" calculators were manufactured they probably just extended the same convention for the smaller keypad. As usually happens with these things, once the standard is established there is no incentive for anybody to change.

Some people have suggested that the telephone companies deliberately made their keypad difficult to use so that the exchange could keep up, but this seems very unlikely to be true.

Q10: Why doesn't Calc have a conversion from teaspoons etc. to ounces?

A: This question crops in many forms, in which a conversion is needed between a measure of volume and a measure of mass. Cups, teaspoons, fluid ounces, pints, litres and cubic feet are all measures of volume, whereas ounces, pounds and kilogrammes are measures of weight (or more strictly mass). Because they are different properties there is no direct conversion; it depends on the density of the substance. For example flour has a typical density of about 600 kg/cu.m, or 0.6 times that of water. From this you can do the conversion. But this density will vary with the type of flour and how it is stored and handled. In many cases a more practical solution is to weigh the container before and after filling to determine the equivalent weight.

Q11: Why is your value for conversion to Btu incorrect?

A: There are a number of different conversion factors for the British Thermal Unit depending on the situation. This is because the definition of the Btu is the amount of energy required to raise the temperature of a pound of water by one degree Fahrenheit. This is dependent on the temperature and pressure (usually assumed to be atmospheric) of the water. To convert to other units of energy you need to specify the temperature, hence the different conversion factors. The variation with temperature is small, and can be neglected for many practical calculations, but it is enough to give slightly different converted values. The default conversion in Calc is a good approximation for typical working conditions, but in each particular industry the adopted conversion factor may be different and this should be used instead. You can add these to the conversion factors in Calc's conversion data if they are not already included.

Q12: How do I calculate the rate of compound interest?

A: There is no built-in function to recover the compound interest rate for a given principal and return. However it can be calculated by taking the nth root of the ratio of the future value (FV) divided by the present value (PV) and subtracting one. Multiply by 100 to give the percentage rate. Here, n is the number of periods (e.g. years if working with annual rates and calculations of interest). Example: If an investment of $100 today results in a return of $150 in 3 years, what is the compound annual interest rate? 150 / 100 =; take the cube root (shift button, then the power/root button, then enter 3); = - 1 = x 100 =; result: 14.47%.

Q13: How do I calculate a logarithm to a base other than 10 or e?

A: To get the log to any base, n, we recommend taking the log (to base 10) and dividing by log(n). Example: to take log to base 2 of 8 : 8 log / 2 log = (result: 3)