Still lookin' for practice, I got my hands on my gf's GRE math book.. seems alright..
I feel like the destroyer didn't give enough permutation/probability/combination problems.
I never finished one of the math destroyer tests timed either. It always took me like an hour to get through those working as fast as possible. I would get like 33ish right before my exam and ended up with a 26 on QR. Just focus on getting the right answer and use other practice tests for your timed practice.