Before I started to tutor in NYC, one of my old students asked me how long she would have to study to get an 800 on the GMAT. I told her that she would be crazy to even think about trying. I meant her no disrespect at all. She is about to start her MBA program at the University of Chicago, so it's safe to say that she's an extremely talented woman. But achieving an 800 on the GMAT is ridiculously tough.
Let's start with some stats from the official GMAT site: fewer than 50 students (out of roughly 250,000) score an 800 each year. If you're keeping score at home, this means than an 800 score would fall somewhere above the 99.98th percentile. And that's assuming that there are close to 50 people who get a perfect GMAT score--the figure could, in reality, be much smaller.
Now, let's talk about the torture that GMAT will put you through if you start to get close to a score of 800. (For the sake of illustration, I'm going to talk mostly about the quantitative section here. The same ideas apply to verbal, but are trickier to explain.) On the GMAT math section, formulas are of limited value on difficult questions. You obviously need to know all of the fundamentals, but it's easy enough for GMAT writers to cook up an evil question that defies formulaic thinking.
At the highest levels, there are some extremely wicked questions. Last time I took the GMAT, I ran into an absolutely brutal series notation question that destroyed me. I spent eight minutes on it, and I still had no idea how to solve the stupid thing. It was so complex that I couldn't even remember the question after the test. And believe me, I was trying like crazy to wrap my head around it, so that I could study it later. Nope.
So basically, the GMAT writers are brilliant enough to lay waste to almost everybody (including arrogant, Stanford-educated GMAT tutors with nearly 10 years of experience), at least some of the time. I might have gotten 35 questions correct on the quant section last time around (though I'm sure that I made some dumb mistakes somewhere... I can say that I was confident in 35 of my answers, and definitely missed at least two questions), and I scored a 51. But the GMAT test can still stump me whenever it wants to, apparently.
And let's talk about that raw quantitative score of 51. I've never heard of anybody getting higher than a 51, and I've been stuck on that score for a long time. Strangely, it's theoretically possible to get a raw GMAT quant score of 60, though scores above 51 will always be rounded down to 51 on your GMAT score report. But I'm pretty sure that I understand what it means to get something higher than a 51: you need to get those evil questions right, somehow. I suspect that the impossibly hard GMAT quant questions would have kept coming last year, even if I'd managed to get that series notation beast right.
I'll go back in to take the test again in the next few months, but the odds that I'll ever get to 800 remain slim. There's absolutely no room for silly errors, and I would have to somehow slug my way through the dirtiest of GMAT questions. You won't, of course, find any truly brual, 800-level questions in any official GMAT material, including the GMATPrep and GMAT Focus tests. So there's no way to practice, really, once you're beyond a certain level.
I'm sure that very few of you are really gunning for an 800 (it won't, in all honesty, really help you get into an MBA program), but I find it fascinating that the writers of the GMAT make it so tough to get a perfect score.