=SUM(OFFSET(Sheet3!$C$2,(ROW()-ROW($A$2))*12,0,12))


assumes sheet2 data starts in row 2. Change $A$2 if required



"dipsy" wrote:

Hi! I want to sum the following:

On Sheet1 I have column of data by year.

On Sheet2 I want to add each year:
Cell 1 - Sum(Sheet1!C1:C12)
Cell 2 - Sum(Sheet1!C1+12:C12+12)

I want to do this so I do not have to keep going back and finding the exact
cell. Can some one please help?

Thanks.