GMAT Tip: Digging for Clues in Answer Choices

GMAT Tip: Digging for Clues in Answer Choices
Harrison Ford hunts for clues in "Indiana Jones and the Last Crusade"
Photograph by Mary Evans/Ronald Grant/Lucasfilm/Everett Collection

This tip on improving your GMAT score was provided by Brian Galvin at Veritas Prep.

While many view the GMAT study process as a trip down memory lane, reviewing algebra and geometry formulas from their junior high and high school days, it’s important to remember that the “GM” in GMAT stands for “Graduate Management.” Although most of the skills tested on the GMAT come from your teenage years, many of the thought processes that are rewarded come from your more recent business experience.

One extremely important set of those skills relates to leveraging assets—picking up on clues embedded within problems and leaning on those clues to help you achieve objectives. A place where you can improve upon that ability is the answer choices themselves.

By this point in your academic career you should know that you can “backsolve” problems by plugging in answer choices to the problem to see if they fit. But a newer skill that commonly leads to success on the GMAT is looking at the answer choices to get an idea of what the correct answer should look like. While many answer choices cannot be easily plugged in or eliminated through the process of elimination, they can often help you determine your first step toward solving the problem. Consider the example:

What is (100,016)(99,984)?

(A) 1010 – 26
(B) 1010 – 27
(C) 1010 – 28
(D) 1010 – 29
(E) (1010)(26)

While your first move might be to scramble for a calculator (which isn’t possible on the test), you should notice a clue in the answer choices: All five involve 10 to the 10th power and 2 to an exponent.  Your goal is set: You have to find a way to take what you’re given and create 1010 out of it.  What are your tools to do so? Well, look at the first four answer choices, which all involve two exponents subtracted. That looks a lot like the “Difference of Squares” rule:  x2 – y2 = (x + y)(x – y).  Given that, you can rephrase the question as:

What is (105 + 16)(105 – 16)?

And since you know you need two to an exponent, you can rephrase the two 16s as 24.  Now you have:

What is (105 + 24)(105 – 24)?

And that, given your knowledge of Difference of Squares (either from high school or from recent GMAT studies), will look exactly like answer choice C.

More important than this example, however, is what you can learn from it. Especially when answer choices involve large numbers and/or algebra, they’re often extremely useful as clues to help you determine how to approach the math. Sometimes your goal is to make the question look like the answers, and the clues embedded within the answer choices are essential parts of getting to work on that goal. The GMAT rewards you for leveraging assets, so recognize that the answer choices are often assets in differing ways:

• Numbers that you can plug back into the problem
• Answers that you can eliminate via the process of elimination
• Clues as to what your “finished” math should look like (as in the example above)
• Far enough apart that you can estimate, using easier values. (For example, if you’re between answer choices such as 279 and 319, try 300 and see if you need a number that’s higher or lower than that)

The GMAT isn’t multiple-choice by accident. Sure, it’s easier to grade that way, but it’s also perfect for questions that reward those who can leverage unseen assets. Be sure to recognize those assets and put them to work.

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