dear all

a question about sumproduct function, in a sheet
A B C
1) 2 0 1
2) 4 5 6
3) 7 8 9
4) 10 11 12

Now I can use 2 sumproduct to make calculation,like
A1*C1+A2*C2 in one sumproduct
A4*C4 in another sumproduct
then I add result together.

My question is, is there anyway to make a formula
A1*C1+A2*C2+A4*C4. I could choose different array then define in more detail
because sumproduct ask all array should have same dimension.

Thanks in advance.