CASIO

The battery needs to be replaced after a specific number of years. Also, replace the battery immediately after display figures become dim.
A low battery is indicated by a dim display, even if contrast is adjusted, or by failure of figures to appear on the display immediately after you turn on the calculator. If this happens, replace the battery with a new one.

1. Press (OFF) to turn off the calculator.

2. Loosen the screws on the back of the calculator and then remove the cover.

3. Remove the battery, and then load a new battery with its plus (+) and minus (-) ends facing correctly.

4. Replace the cover.

5. Initialize the calculator: (CLR)(All)(Yes).