Below you'll find a link to download a PDF of the first chapter of GMAT Math Deconstructed. Ultimately, I'm hoping to post a complete guide to all of the different math topics on the GMAT, creating a map, or toolbox of all of the different skills and information you'll need, to do well on the test.
Chapter 1 (PDF download) covers some introductory basics, and most of the material you will need to know about integers, which is a particular fascination of GMAT question writers. Chapter 2 will cover fractions, decimals and percents. There will probably be somewhere between 10 to 12 chapters, when all is said and done.
For the moment I'm retaining copyright of the material, while I see if it is of any value to all of you out there. If chapter 1 was useful for you, please consider making whatever token donation you think fitting. You'll be letting me know you want to see the rest of the chapters sooner, rather than later, and might reinforce my inclination to put this material out under a Creative Commons CC-BY-NC-SA license.
I'd be happy to hear any questions, thoughts, comments and corrections. Send me an email at gmat@mathdeconstructed.com. Thanks!!