SUM 2 columns Row * Row

Question

I have 2 columns that, starting from row 3, have values I need to sum row * row.

What I mean is something like:

SUM(M3*I3, M4*I4, M5*I5, ecc..)

I found ArrayFormula, but I am not sure its what I need.

user_5632629 · Answer

try:

=ARRAYFORMULA(SUM(M3:M*I3:I))

user_17887301 · Answer

There's the function SUMPRODUCT() specifically designed for this:

=SumProduct(M3:M,I3:I)