Casio fx-991EX (ClassWiz)
The Casio fx-991EX is a scientific calculator with 10 digits precision and formula input logic. It has 552 functions, 60 keys, and an LCD (liquid crystal) display. The power source is Solar + LR44 cell. The calculator was manufactured in China.
Facts at a glance:
|Power Source||Solar + LR44 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.
While holding down Shift and 7 keys, press ON (displays DIAGNOSTIC), release keys, then 6. Then choose from menu.
If you have a Casio fx-991EX that is no longer working, it's probably easiest to just buy a new one, as this model is still currently available.