Summing Alternate Rows

Try this:

=SUMPRODUCT(--(MOD(ROW($A$1:$A$18),2)=1),$A$1:$A$18)

That formula sums odd-row values in the range A1:A18.

To sum even-row values the formula is:
=SUMPRODUCT(--(MOD(ROW($A$1:$A$18),2)=0),$A$1:$A$18)

Adjust the ranges as necessary.

Does that help?

Ron

Thanks so much!! That was so easy. I figured there had to be a simple solution.