Sum of products of two arrays (dotproduct)

First off, I know my title can be formulated better, but my math classes are so far gone I can't remember the correct words anymore..

I need to do something like this (pseudo c#)

int[] digits1 = new int[10]{0,1,2,3,4,5,6,7,8,9};
int[] digits2 = new int[10]{0,1,2,3,4,5,6,7,8,9};
int result = digits1*digits2

This would be the sum of the product of element[i] of each array.

This obviously doesn't work. Any suggestions towards either a better title or the solution?

EDIT clarification: I know I could loop them both and do the math. Basically I would think there is a better way to do this and I'm looking for it purely out of personal curiousity.