Compute datasets (not merge)

[gadget_guru_]

My question is simple, but nevertheless I can't find a solution for it.
I have a bunch of datasets (identical cols and all..) and I want to
"perform calculations" on them.
So I don't want to merge, lets say 2 datasets, but I want to create a
3rd one from 2 datasets that has for example in the 1st col the sum of
the 2 first cols from the source datasets, the 2nd col contains than
the multiplication of the 2, etc ... (always respecting the col's
datatype - they 're all integers by the way)

There must be an easy way to do this ! , I haven't found it yet !

thanks !