Office challenge: How would you sum every other value in a column?

This week, test your Excel skills with this unusual problem. Can you help this user sum every other value?

Users often have unusual requests. For instance, how would you help a user who wants to sum every other value in a column. If the column is short, you can press [Ctrl] and click every other cell, as shown below.

If the column of values is long, this technique is not only tedious, it's easy to click the wrong cells! Can you come up with a solution that's easier to implement than the [Ctrl]+click technique? There's probably more than one way to do this and there are no restrictions on your approach.