What Does It Do ?
This function tests a cell and shows TRUE if there is an error value in the cell.
It will show FALSE if the contents of the cell calculate without an error, or if the error
is the #NA message.

Syntax
=ISERR(CellToTest)
The CellToTest can be a cell reference or a calculation.

Formatting
No special formatting is needed.

ExampleThe following tables were used by a publican to calculate the cost of a single bottle
of champagne, by dividing the cost of the crate by the quantity of bottles in the crate.

Table 1 shows what happens when the value zero 0 is entered as the number of bottles.
The #DIV/0 indicates that an attempt was made to divide by zero 0, which Excel does not do.
Table 1

Table 2 shows how this error can be trapped by using the =ISERR() function.
Table 2