I have a spreadsheet with values from D3 up to AB3 and I would like to sum every 4th cell beginning from D3 (D3,H3,L3 etc..).

I've tried a lot of formulas including SUMPRODUCT, MOD, OFFSET but I always get errors and I believe the reason is because all my cells from D3 up to AB3 contain formulas.

Some of the formulas return numbers and some of them return percentages.

Your help would be much appreciated.