There are several VBA macros here that help you do this:
http://vbaexpress.com/kb/kblist.php
You can search the page for "invoice" and make sure it's an Excel entry.
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Anne Troy
www.OfficeArticles.com

"Holly" wrote in message
...
I'm trying to create a worksheet that, when opened, automatically changes
the
P.O. # to the next number.
Any ideas?