Does anyone have a formula in excel to average every nth cell in a column including the first cell?
For example in the picture if I want to average every 5th cell in the A column it would come out to be 2.75.
Try resolving AVERAGE down to its component parts (i.e. SUM/COUNT),
=SUMPRODUCT(A1:A16, (MOD(ROW(1:16), 5)=0)+(ROW(1:16)=1))/SUMPRODUCT((MOD(ROW(1:16), 5)=0)+(ROW(1:16)=1))