Mapping two integers to one, in a unique and deterministic way

Question

Imagine two positive integers A and B. I want to combine these two into a single integer C.

There can be no other integers D and E which combine to C. So combining

Answer 1

let us have two number B and C , encoding them into single number A

A = B + C * N

where

B=A % N = B

C=A / N = C