Hardest Quantitative questions (Hard for the right reasons...)

Have been using the GMAT Club tests for over 6 months now. Tried them out on holidays ( when they are available absolutely free) and realized that many of the questions required "out-of-the-box" thinking. Went ahead and got a subscription for the same 3 months prior to the test date. These questions are hard for all the right reasons. Extreme values, integers-only assumption, figure not drawn to scale on purpose... such kind of tricks get drilled into the test taker's mind and help in reducing similar mistakes elsewhere. Whenever I have not given a test in a weeks window, I have started making more mistakes which can be categorized as silly. So A must solve repository of tests & questions. However, I do feel sometimes that the scoring is a little on the high side ( Have got Q51 with 5 questions incorrect).

If you are looking for Hard quant questions ( for the right reasons...) go ahead and try the GMAT club tests. They won't disappoint.