I was playing around with these two functions...
=SUM((A1:A10)*(MOD(ROW(A1:A10),2)))
=SUMPRODUCT(A1:A10,MOD(ROW(A1:A10),2))

The first being an array function (you have to press ctrl+shift+enter). The
are both similar to answers already submitted, but I had a question. With
both of these functions I have to use a specified range, I can't use the
whole colum A:A. Why is this?


"Sarah needs to know" wrote:

I have a list of numbers all in one column and I want to be able to type in a
formula that will SUM the numbers in every second cell only, without having
to click on each cell individually. This is how I do it now,
=sum(a1+a3+a5+a7+a9+....etc). Is there a formula that will tell excel to do
this automattically? If so can you tell me how to do it?