I took the GMAT yesterday and am completely shattered and depressed right now. I have no idea how I could score so high on last three practice exams (2 from MGMAT and 1 from MBA Prep - in increasing order mind you) and then get a 640 on the actual exam! I hate to say luck is a factor in the exam but I think it must be! I knew math wasn't going well when I got 4 geometry questions and 2 combinatorics/probability (my worst subjects). Verbal surprised me more than anything as I was scoring btwn 95-99% in my practice exams yet only got 73% in actual exam. I could always narrow my choices down to two and must have picked the wrong one each time. I studied a ton and can't fathom now this occured. Can someone please recommend some other helpful study resources as I've exahusted all the MGMAT Cat exams, books, GMAT Prep materials, etc. or tutoring sessions that won't cost an arm and a leg? Also now that Round 2 deadlines are fast approaching I need essay help. Can anyone recommend which consulting firms are good and provide the best deals economically (relatively speaking since I know they're all pricey).

BTW, I think the MGMAT verbal scoring algorithm is a little off. I noticed I could get 11-12 questions wrong (granted 700 level) but still get 99th percentile verbal score while on the official GMAT Prep software, you can only get 7-8 wrong in order to get a high verbal score.

With a score of 640, I really dont think you have a great shot at making it to a TIER1 / top 20 B school. Are you considering retaking the GMAT? R2 deadlines are around the first week of Jan, so you still have a shot at retaking the exam before it.

The real GMAT is all about nerves, knowledge and a solid strategy. On the D-Day no curve-balls should throw you off balance.

Anyways, shifting gears - I too had a similar experience:
I consistently scored between 700 and 750 on the Prep's, but was blown away in the real GMAT.