GMAT Official Guide was written by the tutors of the exam (GMAC organization). In this textbook you can find everything you should know about the test. It includes descriptions of the sections, the list of things which you have to take to the exam, hundreds of the tasks and the explanation of them.

If you want to pass the test well you should buy GMAT Official Guide, because it’s the only source where you can find the questions which are used in the real exams. Also, it contains some diagnostic tests that can examine your level of readiness to pass the official test, so you can analyze in what areas your knowledge is weaker. The diagnostic test isn’t adaptive but its creators promise that it will be a perfect indicator of your skills.

There’re more than nine hundred tasks and questions in the textbook:

  • GMAT Official GuideSome important details about the new section of the exam and a lot of additional questions;
  • One hundred questions which can help you to determine your level of knowledge;
  • Detailed grammar and math reviews and a lot of practice tasks;
  • Helpful advice how to prepare for the test, etc.

The new 13th edition is the only textbook that includes a lot of question from the Integrated Reasoning (new section of the test).

In the book you can find a special code which opens 50 practice tasks in Integrated Reasoning on the www.mba.com.

Of course, you have to understand that OG shouldn’t be the only source if your preparation, it’s the perfect textbook for the practice tasks, but the theoretical information is quite scarce. That’s why it will be a good idea to learn the theoretical material, pass the diagnostic test and after this begins to practice with the questions which are included in GMAT Official Guide. This method helps you to avoid wasting time and to eliminate your weak spots.

It should be mentioned that all the tasks are arranged in order of their difficulty, so if you do all of them it’s guaranteed that you’ll improve your knowledge.

Anyway, GMAT Official Guide is the really helpful book in which you can find not only a great number of the typical tasks, but also the explanations of them. It’s very important to understand why the answer is wrong; sometimes it’s even more important than choose the right variant.

So OG is a must have book for every candidate. Even if you are going to spend some additional money and buy the others text-books, OG is the necessary thing for your preparation.

Brian Galvin walks GMAT students through some of the strategies to tackle GMAT problems involving squares inscribed within circles: