I've been seeking within forum about starting the GMAT with very limited mathematical knowledge. I did a technical concentration at high school + 4/5 years ago with mediocre results. In contrast to a very, very high outcome on an IQ test I recently took, I might have dyscalculia. Very frustrating. (great (creative, especially with problem solving) abilities in other areas though!). I hope someone is able to guide me with the following. Started last year, but experiencing heavy procrastination.
Planning to take both GRE as GMAT this fall and I'm starting as of today with a fresh, new motivation to aim for a 640690.
Planned test date GMAT: October 2011 (most important)
Planned test date GRE: September 2011 (secondary for a preference program)
Current books for the Math basics:

Kaplan GMAT Math Workbook 
Manhattan GMAT Foundations of GMAT Math Which strategy is wise to follow in this case, especially with understanding the 'why' within GMAT math with limited math knowledge? I have a pretty hard time with the math basics, but it is extremely easy to find relations outside calculations (patterns and such). Probably the most difficult part will be to get used to the basics of both the GMAT as GRE.
Thank you in advance.