I have a bunch of numbers, lets say A, B, C, D. Each number is made up of a
combination of other numbers, lets say 1, 2, 5 make up A, 3, 7, 8, 9 make up
B and so on.

Is there any way I can get an output saying A is made up 1, 2 and 5 in
Excel? I think it could be done using Solver, no?