I personally find math to be one of the subjects where prep books aren't entirely helpful. If I ever get stuck on a topic, I ask a teacher or use Khan Academy, because you can't really cram too much with math. I usually only use prep books for the practice tests, so I purhased the Princeton Review. Normally not a huge fan of PR
, more of a Barron's guy myself, but usually PR
has practice questions most similar to the real deal.