Assuming all your Jan data is in column B of the summary sheet, and all
the Feb data are in column C etc....

I would create the formulas for Jan in the way you describe.
I would make sure that all the B's had $ in front of them (you could
always do a replace all on the columnm, replacing !B by !$B and :B by
:$B

Then when you have created all the Jan formulas in column B of the
summary sheet, copy that column and paste into columns C:M
Then in column C replace all Jan by Feb, in column D replace all Jan by
Mar etc.

Bill Manville
MVP - Microsoft Excel, Oxford, England
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