Hi DelvinGomes,
First off, your prior 650 is a solid Score, so it could be enough to get you into your first-choice School. As such, a retest might not be necessary. Depending on the Schools that you plan to apply to, you would likely find it beneficial to speak with an Admissions Expert about your overall profile. There's a Forum full of those Experts here:
https://gmatclub.com/forum/ask-admissio ... tants-124/The Q42 might be seen as a 'red flag' at certain Programs though - so retesting with the goal of scoring higher in the Quant section makes sense. GMAC has publicly stated that the Official Score that you earn on Test Day is within +/- 30 points of actual ability. By extension, your 2 Official Scores are rather similar - and they show that you essentially performed the same each time (about 640 +/- a few points). You handle certain aspects of the GMAT consistently well, but you also make certain consistent mistakes.
Before I can offer you any additional advice for your studies, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) How long did you study before each of your 2 GMATs? How many hours do you typically study each week?
2) What study materials have you used so far?
3) On what dates did you take EACH of your CATs/mocks and how did you score on EACH (including the Quant and Verbal Scaled Scores for EACH)?
Goals:
4) What is your overall goal score?
5) When are you planning to apply to Business School?
6) What Schools are you planning to apply to?
While the ESR doesn’t provide a lot of information, there are usually a few data points that we can use to define what went wrong on Test Day (and what you should work on to score higher). If you purchase the ESR, then I'll be happy to analyze it for you.
GMAT assassins aren't born, they're made,
Rich