Sumproduct with two different lists

Don’t misunderstand me, you can do this quite easily with List Shifter’s PROCESS List action (go watch the video) without needing code.

You could also do it (in what I think is a more laborious way) with things like Toolbox’s List Item Expression element.

It’s just super painful to explain this to people or to provide a specific examples, but here’s an already existing example page that shows how to do this with List Shifter:

You’ll find a button there to open the editor for that page, as well.

Edit: Also, here’s a painfully detailed explanation of that example, as well: List Shifter: Reverse, Rotate, Swap and ITERATE (Loop) Over Bubble Lists | Now at v1.4: Adds Numeric Option, GET INDEX Action - #438 by keith