I have rows of product data with monthly column headings. Each month, new
data is added. I already have the current month number, but need to extract
the previous month's number but can not use the monthly headings as a
reference. If I have the number "57" for Prod 3, from Nov. 08, what formula
can be used to find the number "12" also from Prod 3, from Oct. 08. Again, I
can not use the monthly column headings as a reference for extraction. Thanks
much for the help!

Aug 08 Sep 08 Oct 08 Nov 08
Prod 1 14 16 9 17
Prod 2 23 42 37 14
Prod 3 37 16 12 57