Is there anyway to sum a range of values given a specific number of
cells you choose to sum. For example you have a range from A1:F1,
G1=number of cells you want to sum from left to right, and H1 is the
total. So if G1=3, then H1=sum(A1:C1) or 16. If G1=5, then
H1=sum(A1:E1) or 20.


A B C D E F G H

1 3 5 8 3 1 7 Var Sum

Thanks in advance.