Create a free account at the MBA website. Test owner GMAC runs this website as the official website of the GMAT.
Access the GMATPrep free software when logging in on your MBA account. Use the free GMAT math lessons included in the software to learn the math concepts needed to excel on the quantitative portion of the exam. The software also has sample questions, explanations and practice tests. You can also use this software to get accustomed to answering GMAT math questions on the computer. GMAC uses a computer-adaptive format to administer the GMAT quantitative and verbal portions.
Buy the "GMAT Quantitative Review, Second Edition" from the MBA online store. As of May 2010, the price for the book and "GMAT Focus Diagnostic Exam" is $38.55 plus $4.95 for shipping. You may order by PayPal or credit card. Learn and practice key GMAT math skills by doing the 300 practice questions and reading the explanations in the review book. Taking the diagnostic exam will provide you an analysis of your strengths and weaknesses in the quantitative portion of the GMAT.
Study a comprehensive math review by purchasing "The Official Study Guide for GMAT Review, 12th Edition." In addition to the math review, this GMAT test prep guide has additional practice questions with detailed explanations not found in the math review guide. You may also do an additional diagnostic exam to assess your progress on the math portion of the GMAT. As of May 2010, the price is $36.95 plus a $4.95 shipping charge, payable online by PayPal or credit card.