This is a user's guide for the CASIO fx-115ES and fx-991ES calculators, which introduces the calculators' functions and usage methods.
This User's Guide provides detailed instructions for using the Casio fx-115ES and fx-991ES scientific calculators. It covers key functions, input formats, safety and handling precautions, and how to access various calculation modes such as CMPLX, MATRIX, and VECTOR.
The manual also describes the LCD display specifications, battery replacement procedure, power‑off behavior, and physical dimensions. Power requirements, battery type, and recommended operating temperature are listed, along with a quick reference for adjusting display contrast and turning the device on or off.
| Solar Cell | Built into the front of the calculator |
|---|---|
| Button Battery | G13 Type (LR44) x 1 |
| Battery Life | Approximately 3 years |
| Operating Temperature | 0°C to 40°C |
| Dimensions | 12.2 mm (H) × 80 mm (W) × 161 mm (D) |
| Bundled Items | Hard case |
Remove the hard case, unscrew the battery cover, take out the old battery, wipe the new battery with a dry cloth, insert it with the positive side up, then replace the cover and screw.
Never charge, disassemble, or short‑circuit the battery, and keep it out of reach of children.