This is the kind of thing you learn in the first lecture of a discrete mathematics class that's required for every single CS program in the world.

It's very obvious if you think about it. If the encoding on the memory is n that doesn't mean it represents "n" data conceptually. It can be n+x for any value of x. For example, you can declare 0 represents $0, 1 represents $0.01, 2 represents $0.02 and so n represents n cents. This is pretty common in tax calculation applications. Then, you can also say n represents n+99^99 so that what GP said holds. They just provided a formal argument for it which proves it by induction, as we call it.