The most important factor in defeating the GMAT – Focused practice

Brent Hanneson - December 23, 2020

The key to maximizing your GMAT score is hidden in the 2021 Official Guide for GMAT Review (aka the OG2021), on the first page of the math review (page 17):

Keep in mind that this knowledge of basic math, while necessary, is seldom sufficient in answering GMAT questions. Unlike traditional math problems that you may have encountered in school, GMAT Quantitative Reasoning questions require you to apply your knowledge of math. For example, rather than asking you to demonstrate your knowledge of prime factorization by listing the prime factors of a number, a GMAT question may require you to apply your knowledge of prime factorization and properties of exponents to simplify an algebraic expression with a radical.

The example involving prime factorization is great. Here’s another example: every test-taker must know how to factor a difference of squares, x² – y² = (x + y)(x - y), but it’s incredibly unlikely (unless your test is going horribly wrong) that you’d get a question like “Which of the following is equivalent to x² - y²?” Instead, you may be asked to evaluate an expression like 433² – 432², in which you can avoid some time-consuming calculations by recognizing that this is a difference of squares and, as such, can be factored to get (433 + 432)(433 - 432), which evaluates to be (865)(1), which equals 865.

A bigger challenge is to spot the differences of squares hiding in this official question:

Original Question.png

For this question, we must first recognize that 0.99999999  = 1 - 10^(-8) (a difference of squares) and that 0.99999991 = 1 - 9 x 10^(-8) (also a difference of squares) to get:

Solution.png

This is a super (duper) tough question, BUT, now that you’ve seen it (and its solution), you’ve added another tool to your mathematical toolbox. As you may have guessed, there are many different ways to test the difference of squares property. For example, here’s a 550-ish level question, a 650-ish level question, and a 700+ level question.

Given the wide range of ways to test this single concept, how can you prepare for every possible way in which the GMAT can test your understanding of difference of squares, along with every other property?  Through focused practice.

Focused practice

A lot of students prepare for the GMAT by answering random/unrelated practice questions (a geometry question, then a statistics question, an algebra question, a geometry question, etc.). This strategy doesn’t allow you to fully explore the intricacies of each concept. A marginally better approach is to focus on practice questions related to broad topics such as Statistics or Geometry, but this approach still falls short, since you don’t get the chance to explore the different ways to test each individual concept. So, for example, if you’re studying Geometry, I recommend that you first focus on questions involving parallel lines, then move on to general triangles, then right triangles, then similar triangles, and so on.

Practice questions beneath each video lesson

Beneath each video lesson in my course, you’ll find a Reinforcement Activities box containing linked practice questions that test the handful of concepts covered in that video lesson. So, for example, under the video lesson on Quadrilaterals, you’ll find dozens of practice questions that test only those concepts related to quadrilaterals. These questions will show you the many different (and devious) ways the test-makers can test this one micro-topic. The same applies to the video lessons on Standard Deviation, Percent Increase/Decrease, and so on. So, the more of these practice questions you answer, the better prepared you’ll be on test day.      

Final Words

No prep course or tutor can prepare you for every possible way the GMAT can test your skills, but this kind of focused learning will help you understand the nuances and intricacies of each of every concept so that you’ll have the conceptual flexibility needed to tackle unconventional questions.