Hi,

Try this

=SUM(IF(MOD(ROW($A$1:$A$100),3)=0,$A$1:$A$100,0))
It's an arry so commit with
Ctrl+Shift+Enter

Change the 3 to a 2 to do every second row

Mike

"Mario" wrote:

How to sum every 2nd or 3rd row on the easiest way?