Hewlett-Packard HP 21S (Pioneer MONTE CARLO)
The Hewlett-Packard HP 21S is a programmable calculator with 12 digits precision and algebraic logic. It has 170 functions, 37 keys, and an LCD (liquid crystal) display. The power source is 3x1.5V cell.
Facts at a glance:
|Power Source||3x1.5V cell|
Note that diagnostic tests generally delete any data on the calculator. Be sure to back up any important information held in the calculator before running these tests.
Hold down ON button and press fourth key on top row of keypad, then choose test from menu (use EXIT to leave test and go back to menu). Use ON and fifth key on top row to run a test sequence. Use ON key and third key on top row to reset calculator after tests.
If you have a Hewlett-Packard HP 21S that is no longer working, you can first try replacing the 3x1.5V cell batteries. If that doesn't solve the problem, then you can consider replacing the calculator with a modern equivalent. We suggest the following current model as a replacement: