I have found the following exams to be accurate (in order):

1.) Official GMAT Test

2.) Manhattan GMAT Exam

3.) Veritas Ultimate Test

4.) Platinum GMAT Practice Test

Thank you for posting the very helpful tutorial. I think that data sufficiency questions can be a bit challenging initally since the question format is unique and not familiar to most people. I also found a host of data sufficiency gmat practice questions (see link) that might be good for practice. ...

GMAT Idiom List (from Official Guide)

Here is a GMAT Idiom list composed of problems from the Official Guides. It is very thoroughly documented. This helped me a lot.

Also, you should download the official guide prep test and go through all the sentence corrections.

I found the following GMAT AWA Template, used it, and got a 6. Can't promise it will work for you, but it was magic for me.

Too late to work with you on Round 1?

I am interested in applying for round 1 @ Harvard, Stanford, and MIT. However, I am wondering whether there is enough time to work through the process with you. In other words, if I pay the money, could we do put together a good application by round 1. What I Have Done Thus Far: -Taken the GMAT -Spe...

660 -- help please

I recently took the GMAT and scored a 660 (45Q 34V). This was a major disappointment as I had done the following over the course of the past two months: --OG 11th Edition PS & DS (did twice) --OG Quant Review (did twice) --ManhattanGMAT class & books I scored 680 on an official practice test...