ALL GMATPrep questions QUANT/Verbal

Answering official GMAT quant questions often doesn't require much math knowledge. As long as you understand things like basic algebra, how to manipulate fractions, and some basic geometry facts, you know everything in terms of math that you need to know in order to answer many or even most official quant questions. Further, even in the cases of questions of the more advanced types, such as permutations or advanced overlapping sets, the math and calculations necessary for answering them tend to be pretty simple.

At the same time, however, official GMAT quant questions can be rather tricky. For instance, an inequality based question can be based on a relatively simple inequality and yet have a twist that makes getting the right answer tricky.

Many practice quant questions are more mathematically complex than most official quant questions or are such that answering them requires taking more steps or doing more calculating than is required for answering official questions.

So, if you are skilled at seeing the angles, or tricks, in official quant questions, they can seem rather straightforward or even easy, because you don't need to do much calculating or deal with much math, and they can be way easier for you than some practice questions.