Insert or use an empty column to the left of your data set.

In that column use the formula... "=COUNTIF(D5:$D$19,D5)" and fill down.
The above assumes invoice IDs in D5:D19 (note the use of $).

Assuming the above formulas are in column C and the amounts to total
are in column E, then your "Total" formula is... =SUMIF(C5:E19,"=1",E5:E19)

Jim Cone
San Francisco, USA
http://www.realezsites.com/bus/primitivesoftware
(Excel Add-ins / Excel Programming)



"Garbage Man"
wrote in message
I want to calculate a total that avoids certain duplicate information, like
an invoice number that may repeat. I have a list of daily invoices but the
same invoice number may come up twice for various reasons. I only want to
calculate its total once.