[twoodfin]

This is a much-debated question in the philosophy of mathematics.

One of the stronger arguments that the real numbers were discovered, rather than invented, is their “unreasonable effectiveness” in aiding our exploration and understanding of the physical world.

The same can’t be said for equally abstract but clearly invented concepts such as the rules of chess.

[vlovich123]

I think it’s a mixture of both, but using its ability to explore the physical world as the benchmark seems myopic because math can be used to describe universes other than our own. Our universe just happens to be the one we focus on because that part of mathematics is particularly interesting, but if anything it means the structures we put in place to manage that aspect are invented not discovered.