Count # of times the same number shows up in Excel spreadsheet

[Kasimir867]

I'm trying to show on one worksheet the # of times a duplicate item # has
shown up on another worksheet. This is to be used as a visual "warning" that
the same item number has been placed on the worksheet, to possibly prevent an
overload of product.

 

[Dave Peterson]

Maybe you can use =countif()

=countif(sheet2!a:a,x99)

will count the number of times the value in x99 of the activesheet appears in
column A of sheet2.