GMAT Reading Materials
Everyone preparing for the GMAT will need some kind of published material - sample GMAT questions, math review, etc. Some tutors produce handouts for students, and several publishers produce GMAT books.
The quality is haphazard - some GMAT materials are excellent, some appalling. If you have an excellent personal tutor, and he or she provides texts and sample questions to supplement your classes, these materials might be better than anything available on the market - especially since they will complement your lessons.
If you are buying a book from a Test Prep publisher, there are a few things to bear in mind:
One book that is essentially mandatory is the Official Guide, which contains hundreds of real GMAT questions. If you want practice questions just like those on the test, this is the best source (along with the freely downloadable sample GMATs from mba.com, the PowerPrep package, and the retired paper tests).
We would not recommend looking at a general high school math primer to get ready for the test - it's far better to get a book specifically about the GMAT test. Otherwise you risk missing topics that are important, or learning methods that are inappropriate for the GMAT.