While trying to understand what the competency floor will be for math teachers next year in middle school, I came across the question below on the skills test.
My question here is to clarify what is meant. Specifically, what is the difference between these two sets:
- all positive integers
- all positive integers writable in form $2^n * 3^m$
Original question: S is the set of all positive integers that can be written in the form $2^n * 3^n$, where n and m are positive integers. If a and b are two numbers in S, which of the following must also be in S ?
(assuming answers aren't relevant, question posted only for context)