Casio SF-5580 Owner's Manual page 66

To correct errors in calculations
If you enter a wrong value, press C/AC once and then enter the correct value.
If you press the wrong arithmetic operator key ( !, @, #, $), simply press the correct
key before entering anything else.
About calculation errors...
Whenever an error occurs, the indicator "ERROR" appears on the display.
When the number of digits in the mantissa of an intermediate or a final result
exceeds 12 digits.
When the number of digits in the mantissa of a value stored in memory exceeds
12 digits. In this case, the Digital Diary automatically retains the last value stored
that did not exceed 12 digits.
Division by zero.
To clear errors
Press C/AC once to continue with the same calculation. If you want to clear the
calculation and start again, press C/AC twice.
To enter the Calculation Mode
Press } to display the initial Calculation Mode screen.
Example 1: 21 + 3 = 24
Example 2: 11 + 10% = 12.1
– 64 –