try this idea where a11 has 1,2,3,4,5,etc

=SUM(B12:OFFSET(B12,1,A11-1))

--
Don Guillett
Microsoft MVP Excel
SalesAid Software

"Flanno" wrote in message
...
I am trying to sum a certain number of columns, based on the criteria in a
certain cell.

If my criteria is an "8", I want to sum the last 8 columns of an array.
If
I change the 8 to a 9, I want the sum to automatically pick up the last 9
columns,if I change it to 10, I want the sum of the last 10 columns, etc.

Can anyone help????