Couple of things. I've never seen a math score higher than 51, and that's 99th percentile. Minor point - but just FYI.
When you took practice tests, did you do the essays? On the real test, did you take the breaks and have something to eat? I ask because the most common reason I see when people have a drop in verbal on the official test is that they run out of steam because they didn't prepare adequately for the stamina aspect of this test. So just wondering whether that might have happened with you. Did you feel like you had less energy than usual during the verbal section?
Also, in your prep, be really careful NOT to focus just on 700+ level questions. On this test, you have to earn the right to get those questions, which means you have to be able to handle all (or most) of the 600-700 level questions. If you keep missing those for whatever reason (careless mistakes, etc), then you won't even lift yourself to a level where you'll be getting 700+ questions.
It's also the case that you essentially build your abilities from lower to higher level questions of the same type. So mastering 600 level circle questions can help you handle 650 level questions and mastering the 650 level questions will help you at the 700 level.
In terms of key topics tested, I just posted that for someone else - check out this thread:
http://www.manhattangmat.com/forums/stu ... t4162.html
In math, if you do earn 700+ questions, you can expect to see both harder questions of those same types, problems that will combine multiple hard concepts, and additional things like:
- statistics (eg, something that will expect you to understand how standard deviation works)
- advanced concepts within the normal categories (eg, weighted averages instead of just basic averages)
- "weird" quadratics (to the 4th power or the 1/2 power instead of simply squared)
- pattern problems in which the calculations are obviously too massive to be done without a calculator (eg, the units digit of (3^42)(7^14)
and other fun stuff like that :)
Also, remember that you don't actually need to get a ton of the 700+ level problems right in order to get a 700. You need to get most of the sub-700 questions right and only some of the 700+ questions.