create a rolling sum??

D

dustin

I need to create a rolling sum always taking the last 30 entries(cells) and
adding them up. Basically to keep an accurate "last 30/60/90 days sum" is
there a formula to do this?? using dates or just cells?
 
M

MarkN

How about

=SUMIF(A4:A17,">"&D1,B4:B17)

where A4:A17 contain the dates, D1 contains the date 30/60/90 days ago and
B4:B17 contain the data you want to sum.
 
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