Hi,

Try

=SUM(OFFSET(A2,,COUNT(A2:P2)-1,,-4))

Mike

"Eddie" wrote:

A B C D E F ......... AA
Name Jan Feb Mar Apr May........
1 a 10 9 22 15 15
2 b 12 3 11 18 12
3 c 12 11 16 17 23
4 d 23 22 12 21 22

I am using office 2007,I will enter the figure every month into this
worksheet. what formula should I use to sum the latest 4 months of figure and
show it in column AA?

Thank you