Cause: A nonnumeric argument is used in a function that requires a numeric argument.
Solution: Make sure that the arguments used in the function are numbers.

Doubleclick the cell that contains the #NUM! error.

Delete any nonnumeric characters from the numeric arguments in the formula.
For example, if the value you want to enter is $1,000, enter 1000 in the formula.
Cause: A function that iterates, such as IRR or RATE, cannot find a result.
Solution: Change the number of times Excel iterates formulas.

On the Excel menu, click Preferences.

Under Formulas and Lists, click Calculation , and then under Iteration, select the Limit iteration check box.

In the Maximum iterations box, type the number of iterations that you want to set as the maximum number of times Excel recalculates.
The higher the number of iterations, the more time Excel needs to calculate a sheet.

In the Maximum change box, type the amount that you want to set as the maximum amount of change between calculation results.
The smaller the number, the more accurate the result and the more time Excel needs to calculate a sheet.
Cause: The formula produces a number that is too large or too small to be represented in Excel.
Solution: Change the formula so that its result can be represented in Excel.
Excel can represent values between 1*10^307 and 1*10^307.