The Excel #N/A error is produced when a value is not available to your formula.
The Excel ISNA function tests if an initial supplied expression (or value) returns the Excel #N/A Error, and if so, returns TRUE; Otherwise the function returns FALSE.
The format of the function is :
Where the value argument is the expression or value to be tested. This can be either supplied directly to the cell, or can be a name or reference for a cell containing a value or formula.
The following spreadsheet shows examples, of the Excel Isna function, used to determine whether a value or expression returns the #N/A error.
The format of the functions are shown in the spreadsheet on the left and the resulting values are shown in the spreadsheet on the right.
The above examples use different argument types, including:
Note also that, in the above examples:
Further information and examples of the Excel 'Is' functions can be found on the Microsoft Office website.