Just noticed you said the data is in a row. Change the formula to
this:

=SUMPRODUCT(--(MOD(COLUMN(A2:AA2),3)=0),A2:AA2)

This looks at row 2 and adds every third column from C onwards.

Hope this helps.

Pete

On Sep 19, 3:16*pm, Pete_UK wrote:
Try this:

=SUMPRODUCT(--(MOD(ROW(A1:A100),3)=0),A1:A100)

Assumes you are trying to add from column A - adjust to suit. It will
add rows 3, 6, 9, 12 etc.

Hope this helps.

Pete

On Sep 19, 3:02*pm, baurian wrote:



Hi,

I need to add every third value in a row of data and I do not know how.

Thank you,

Benedict- Hide quoted text -

- Show quoted text -