Hello folks,

I'm hoping someone can help me since I have hit a snag in trying to modify a
formula.

This formula is working now (in J3) to sum starting with the value in row 11
and then adding every 7th row: =SUMPRODUCT((J11:J221)*(MOD(ROW(11:221),7)=4))

I want to adapt this (in O4) to sum starting with the value in row 17 and
then add every 13th row. I've tried
=SUMPRODUCT((O17:O407)*(MOD(ROW(17:407),13)=3)) but I get #VALUE. I'm
guessing the problem is with the =3 at the end of the formula but I can't
figure out what it should be. Any ideas?

Thanks,
Denise