ISNA

What Does It Do?
This function tests a cell to determine whether it contains the Not Available error #N/A.
The #N/A is generated when a function cannot work properly because of missing data.
The #N/A can also be typed in to a cell by the user to indicate the cell is currently empty,
but will be used for data entry in the future.
The function is normally used with other functions such as the =IF() function.

Syntax
=ISNA(CellToTest)

Formatting
No special formatting is needed.