Below is a challenging GRE question. However, instead of just having you take a blind hack at it, I want to provide a little bit of context.

First off, if you sense that a question is very difficult on the test – be it a verbal or quantitative one – then skip it. Because the new GRE allows you to skip, you should take advantage of this option when you encounter a question that you either have no idea how to approach, or sense that you can probably get the answer, but doing so will be time consuming.

The good news is, each question is worth the same number of points, so even if you blindly guess on a really difficult question, the worst that can happen is you guess incorrectly, and simply only lose one point. The worst that can happen is, you become so caught up in solving one problem that you miss attacking any number of easy questions that you could have answered correctly, had you not burned your precious minutes on the difficult question.

The key is learning to gauge when a hard problem is truly a difficult one, and when you are simply stressed because of the nature of the situation (you are taking the GRE, after all). The best way to prepare for this is by doing practice problems, and practice tests, so you get a sense of where it is advantageous to skip, and where it is better to see a problem through till the end (usually, if you spend a minute staring at a problem without any noticeable progress, it is time to move on).

Now that I’ve finished prefacing challenging questions, try the following one. And, in this case, don’t simply give up after a minute – this isn’t the real test, so you can spend a few minutes. The important part is how you approach the problem. Remember, taking an approach and following through on it is better than simply staring at the screen, and rereading the problem over and over again. Good luck!

A “descending number” is a three-digit number, such that the units digit is less than the tens digits and the tens digit is less than the hundreds digit. What is the probability that a three-digit number chosen at random is a “descending number”?