ISERROR
Description
ISERROR determines if the specified expression returns an error value.
Syntax
ISERROR ( expression )
| Parameter | Description | 
| expression | Any expression. | 
Remarks
If the expression returns any error value, such as #N/A, #VALUE!, #REF!, #DIV/0!, #NUM!, #NAME?, or #NULL!, True is returned. Otherwise, False is returned.
Examples
This function returns True:
ISERROR(4/0)
This function returns False if A1 contains a formula that does not return an error.
ISERROR(A1)
Also, see