Trust the worldwide bestselling study guide to help you prepare for the GMAT!. The Official Guide for GMAT Review - 12th Edition. Here's what you'll find inside the only book on the market written by the creators of the exam.: More than 800 questions from past GMAT tests - including 250 that have never before been published; Full answers and detailed explanations for all questions; Grammar review covering concepts tested on the GMAT Verbal section; Comprehensive math review of the topics tested on the GMAT Quantitative section; Actual essay topics, sample responses, and scoring information; Qu.