How to find duplicate invoices when the duplicate may contain a letter?

Hi all,

Hoping you can help me here, I'm no expert in excel.

I have a query of about 16,000 invoices based on what I consider possibly important..

-Date
-Invoice Number
-Amount
-Vendor
-GL acct

The problem is A/P clerks will sometimes add a letter to the invoice to bypass the internal control (won't allow you to enter duplicate invoices), so there may be an invoice #240 and #240a and they both end up getting paid but really it's only 1 invoice. What would you suggest in order to find these?

Thanks for any input!

Assuming invoice numbers in column A, this formula will give a count of invoices that are the same except for a letter added to the end

=COUNTIF($A$1:$A$20000,A1&"?")

Thanks,

Issue is, a lot of the invoice numbers are the same but they are for different vendors so in this case it's ok to be duplicated. How would I break it up depending on vendor?

Edit - Found a problem with my post and deleted.

Here we go. The following formula will return a 1 for entries where the vendor is the same and the invoice has a character added. Vendors are in column A and invoice numbers in column B. Put the formula in C2 and copy down.

=COUNTIFS(A:A,A2,B:B,LEFT(B2,LEN(B2)-1))

Nice! that's what I'm looking for Canuck Chuck, I'll try that out as soon as I can.