Thanks for your help. I will provide a description of what I need to do.

I need a weighted average - average of row 6, weighted by row 3 (those rows are fixed, it will always be row 6 and 3).

If I didn't have to worry about the columns, the complete formula would be **=SUMPRODUCT(3:3,6:6)/SUM(3:3)**

The trouble is, as I described above, that I need to include in the calculation only certain columns, but those columns will vary each time we retrieve this data. The way we mark those columns is with a range name ("myrange" in my example). In case it's relevant, the columns we need to include in the calculation will be at a certain interval (every 2nd column, or every 3rd column, etc.), but that interval will also vary each time we retrieve the data, and there's no indicator in the data itself what that interval is.

Any ideas how I can accomplish that?