I second this. I did my first math exam (Linear algebra 1 and 2) while trying to minimise memorisation and it didn't work out so great (passed, but barely). You have to memorise, to really understand it you also should be able to do a proof, but you need to memorise it. It's too much and too complicated to do it on your own, especially in the exam. Normally you don't have a ton of time and event the most simple theorems take time to work out on your own (and sometimes you just get randomly stuck, it just happens). Don't underestimate the work that went into calc 1 or 2, just because you can follow the derivation and proof does not mean one can define the theorem in the equal amount of time.