=SUMPRODUCT(--(INT((MONTH($A$2:$A$13)+2)/3)=1),$B$2:$B$13)

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__________________________________
HTH

Bob

"Narnimar" wrote in message
...
What is the formula for getting the monthly & quarerly sum for the below?
A2 B2
01/01/2008 43
02/02/2008 32
03/03/2008 43
04/03/2008 54
05/04/2008 5
06/05/2008 32
07/06/2008 75
08/07/2008 3
09/08/2008 23
10/08/2008 64
11/09/2008 76
12/09/2008 43