"Myrna Larson" wrote in message
...
MOD would work in the case of A1, A3, and A5, where you want every-other
column. The array formula would be

=AVERAGE(IF(MOD(ROW(A1:A5),2)=1,IF(A1:A5<0,A1:A5) ))

But that will not work for the example/solution you posted most recently,
which refers to cells C26, G26, and K26. The column numbers are 3, 7, and
11,
so there's no numeric relationship between them.

Actually, the relationship is +1 = 4*1, 4*2, 4*3.

Rgds,
Andy