How can I Multiply two columns then add them together easily?

Question

I would like to Multiply Column A with Column B. There is data for each column in rows 3-20.

Rather than doing (A3B3)+...(A20B20), is there an easier and more efficient way of doing it?

Answer 1

I actually just figured it out. What I want to do can be accomplished with the SUMPRODUCT forumula.

=SUMPRODUCT(Select Column A Values,Select Column B Values)