Surely your formula should be:

=SUMPRODUCT((O17:O407)*(MOD(ROW(17:407),13)=4))

It then works for me. Do you have #VALUE! in your data anywhere?
--
HTH

Sandy
In Perth, the ancient capital of Scotland
and the crowning place of kings


with @tiscali.co.uk


"denise" wrote in message
...
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