CASIO

Perform the following steps whenever an error occurs during a calculation or when calculation results are not what you expected. If one step does not correct the problem, move on to the next step.
Note that you should make separate copies of important data before performing these steps.

1. Check the calculation expression to make sure that it does not contain any errors.

2. Make sure that you are using the correct mode for the type of calculation you are trying to perform.

3. If the above steps do not correct your problem, press the key. This will cause the calculator to perform a routine that checks whether calculation functions are operating correctly. If the calculator discovers any abnormality, it automatically initializes the calculation mode and clears memory contents. For details about initialized settings, see "Configuring the Calculator Setup".

4. Initialize all modes and settings by performing the following operation: (CLR)(Setup)(Yes).