Assuming these are some type of identifiers you can go to an adjacent column
and do in B1

=countif([Book2.xls]Sheet1!A:A,A1)
then drag fill down the column

in book2 in B1 you could do

=countif([Book1.xls]Sheet1!A:A,A1)
and drag fill down the column.

zeros would indicate the item is unique to that workbook.

--
Regards,
Tom Ogilvy


"Jay Jones" wrote:

> I have to compare 2 lists of numbers every month and find the difference
> between them