Functions across multiple worksheets
 

I have three seperate worksheets ( all in the same workbook) that I need to
compare against a fourth.

Basically I have a master worksheet with a list of part numbers from a
recent job. The three other worksheets are lists of part numbers from
previous jobs for the same company. I need a way to figure out if a part
number from the the master appears anywhere on the other three. I've tried
various vlookups, if/thens, etc and am having no luck. The function appears
to work, but returns a false value when I know for a fact the part number in
the master appears in at least one of the subsequent worksheets.

Can anyone help? Is it even possible to compare a single cell in a master
worksheet to multiple cells in multiple worksheets? The worksheets are all
formated the same.