Is it discovered or invented?
When natural scientists like Archimedes ran naked on the streets of Syracuse, he proclaimed “Eureka!” (I’ve found it.) But what should mathematicians proclaim when they complete the proof to a profound theorem? “I’ve found it,” or “I’ve made it?” Is 1+1=2 in other universes, or even when the universe does not exist? (Whatever that means…)
It helps a little to watch this (layman’s) video on whether numbers exist.