One common mimicking approach in this situation is to remember a (very) large number of math questions, such that the vast majority of new questions will be from this set of very similar to its elements. However, given a slightly non-trivial math question, albeit an easy one, a mimicking system will fail. The system will still be (kinda) practically useful but not trustworthy.
That’s like saying “Oh, you didn’t get the right answer to that math question, you just mimicked giving me the right answer”. Yeah, but if I gave you the right answer, then I gave you the right answer, and I must’ve gotten it somehow.