what about not native speaker + weak quant skills ?

I am sure you will still benefit from our verbal study discussions but this category of people will be studying and discussing MATH in a different level. Most of these people with good quant skills can score 45+ without even studying GMAT. But the journey from 45 to 51 is tough!

interesting....i'd like to score a 45 on quant....

Quant Study:

Materials used:

a) Manhattan GMAT's guides

-Number Properties ( it is very important to learn the fundamentals!)
-Equations, Inequalities ad VIC's
-Word Translations
-Geometry
-Fractions, Decimals & Percents

These books are great to brush up the math knowledge and learn the GMAT math.

b) OG 11 and OG Qualitative Review

It is important to have a good accuracy and timing for the last 50 questions of each section in both books. The first 2/3 questions are just good warming up. And if you start your test strong, you will only see the tougher questions in the rest of the test.

c) GMAT Paper Tests:

Great numbers of questions to practice. I believe in quality of study is more important than quantity of the study. But in quant study, the more problems you solve, the more comfortable you become.

d) www.gmatclub.com math challenges.

Great set of questions for those who target at 50-51.

e) Manhattan GMAT question banks + CATs

You will find them very time consuming and tougher than real GMAT questions but they sure will make your real GMAT experience like a walk in the park.

f) KAPLAN 800 - PS & DS

It is great book to double check you know most of the nasty GMAT traps and feel confident.

Please feel free to add any other sources.