You definitely have gone through quite a few problems. Do not worry, there are still many other questions available. First off, there is the 13th. edition Official Guide. Some may kvetch that it only contains a hundred or so new questions, but remember: those questions are the most recent and give us a sense as to what GMAT is up to in the question concocting department. Kaplan 800
offers a few practice questions math-wise, though there Data Sufficiency section is disappointing (it only has 18 questions). There are also NOVA GMAT questions (which tend to be quite difficult) and then of course GMAT prep questions, which are retired (read old) GMAT questions.
If you want more practice with computer-based questions (and have already taken the GMATPrep tests
) then try out Magoosh
. We offer hundreds of practice questions in quant that are just as hard, if not harder, than those found on the actual test.
Hope that helps
Magoosh Test Prep