Try this:

Assuming your data start from A1
In B1 =IF(MOD(A1,3)=0,SUM(INDIRECT("A"&1*ROW()-2):OFFSET(A1,0,0)),"")



"Mujeeb ur Rehman, FBL-GRW-PK" wrote:

There are 12 figures in a column (A1:A12). B1 is a parameter Cell. when I
enter 3 in the parameter cell (B1), result must be {sum(A1:A3), sum(A4:A6),
sum (A
7:A9), sum(a10:a11)}. I Mean to say sum function must be handled with the
paramenter cell (B1), and result will be in other column with parameter
interval i.e., value of (B1) i.e., 3 or 6 or 9 or 1 etc.