eYsYs,
I studied math and physics for undergrad, so I was hurt when I got a Q47. I have since retaken the test, and received a Q49. If you're like me, and have a strong background in math, then you probably try to leverage your past math experience to quickly process the Quant problems. I discovered that this was causing me to make many errors on the higher level Quant problems. For example, there is a category of DS questions that gives you two questions, and attempts to make it a look like a C/E answer. But upon further review, it actually is a A/B answer because the criteria in the question allows only for integers, +/-, perfect square, prime, ect, and this creates a condition that allows one of the choices to be sufficient.
I feel like the GMAT really punishes those who have a strong math background because the GMAT writers know that we can quickly look at a problem and discern how many solutions it should have. So they create conditions that look to have many solutions, but through a careful analysis, the conditions set forth only allow one solution. On my most recent test there was a question that appeared to have no solutions, choices A + B looked almost the same, and right as I was about to hit E, I realized that it was a trap question and took a minute to actually solve A and B for the conditions in the problem, and realized that one of them actually worked.
Most of this stuff seems like common sense, but the math that the GMAT gives you when you get to the higher levels of quant is more about tricks and conditions than it is about computational power.