## Overview

If there's one quant topic that scares the vast majority of GMAT test takers, it's combinatorics. This is because very few of us have been exposed to these special counting problems, often made even more difficult by mixing in bits of probability theory. The fact that they are rarely featured in depth in most GMAT prep guides is also a reason why combinatorics and probability questions are feared by students. The Veritas Prep Combinatorics and Probability book is however an exception, since it provides a detailed theoretical review of the topics and consistent practice.

The book starts out with the most basic concepts about counting principles and builds up to more complex topics such as circle arrangements. It also contains 13 drills and 82 GMAT-style problems, out of which 13 are Data Sufficiency. This is really important especially for test takers seeking a high score in quant (48+), who often complain about the scarcity of high quality combinatorics problems.

## Pros

• In depth coverage of a topic considered advanced. What I liked the most about this book is that it really explains combinatorics starting from a basic level and up to more difficult subtopics.
• After each new formula or strategy, the authors offer one or two examples illustrating what you've learned. This is a really efficient method of study since it allows you to firmly grasp new concepts.
• Hefty amount of practice, which makes this books especially suitable for GMAT hopefuls aiming for higher quant scores. 15 questions are also designed to be the toughest of the tough and are labeled as challenges.
• Some problems test more than one concept, a fact that makes them all the more interesting. The explanations are also of consistently high quality to help you understand no matter your level.

## Cons

• More Data Sufficiency would have been a plus. While it does contain the most combinatorics and probability DS (13 questions) in all the guides I have reviewed so far, there's always room for improvement. This is because on test day, over 40% of the questions in the quant section will be DS and my opinion is that this percentage should be mirrored in the amount of practice available.
• The authors sometimes make the recommendation to simply write down all the favorable cases for a given question. I am personally not a big fan of this strategy and advise against it most of time because under the pressure of a timed exam you might lose too much time or miss a case or two which would lead to a wrong answer.

## Bottom Line

The Veritas Prep Combinatorics and Probability book gets five out of five stars. This is really one of the most thorough books I've seen on the subject of GMAT combinatorics and probability. As such, it is an excellent investment no matter your current level in quant, since you'll undoubtedly see at least a few problems involving combinatorics and/or probability. The mix of theory and practice in the Veritas Prep Combinatorics and Probability book will help you tackle these difficult question types with ease.