I wish to multiply then add arrays of numbers of different size.

eg
array 1: A1:C1
array 2: A5:A8

where the answer equals
(A1*A5)+(A1*A6)+(A1*A7)+(A1*A7)+(A1+A8)+(B1*A5)+(B 1*A6)+......(C1*A8)

Is there a simple way to do this?

Cheers Aitchy