Some calculator operations cannot be performed under certain conditions (for example, divide when X-register = 0). If you attempt such an operation under these conditions, the calculator will display the word Error followed by a digit, 0 through 8. Listed below are the definitions of each error number.

0 Mathematics error. When HP12c Platinum Calculator attempt to divide by zero. Also operations which would result in complex numbers (example: SQRT(-1)).

1 Storage Register Overflow. When performing storage register arithmetic the magnitude of a result is greater than 9.999999999E+99 may occur on the HP12C.

2 Statistics. Trying to perform a statistics function or linear estimation on the HP12c Platinum Calculator when improper condition exists.

3 IRR. The calculation of IRR is very complex. This error indicates that the given initial guess was not sufficiently close to the correct value. Make a guess for the interest rate and key it in. On the HP12c Platinum Calculator, press RCL g R/S to enter the new guess into the calculator. Then press f IRR. This guess value is not held in continous memory, and is only valid during the current session.

4 Memory error. Attempting to enter more than 99 program lines into the HP12c Platinum Calculator .

5 Compound interest and depreciation errors.

6 Storage registers and discounted cash flow register errors.

7 IRR. No answer exists for the given cash flows.

8 Calendar function errors. Usually date format is incorrect. When in D.MY mode the date must be entered via the following format: dd.mmyyyy and when in M.DY mode: mm.ddyyyy.

Pr Error Continous memory has been reset. Displayed when the program is started and cannot find an initialization file, usually placed in the default program directory. This is a way to reset Continous Memory: simply delete the initialization file before starting the program. All registers are set to zero and program memory is filled with the g GTO 00 instruction.

At any time a number is too large to be displayed in the display, the display shows 9.999999 99. This means that the last operation resulted in an overflow condition. If that should happen when a program is running the program will halt. Also when an operation results in a number less than 1E-99 then that number is replaced by zero.