GMAT Tip: Dos and Don'ts of Math Problems

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The GMAT Tip of the Week is a weekly column that includes advice on taking the Graduate Management Admission Test, which is required for admission to most business schools. Every week an instructor from a top test-prep company will share suggestions for improving your GMAT score. This week’s tip comes from Tracy Yun, founder and chief executive officer of Manhattan Elite Prep.

Data sufficiency questions are among the GMAT’s toughest. Typically they present a question and two statements, then ask which of the statements (if any), alone or in tandem, are sufficient to answer the question. Here are five tips for tackling these and other quantitative questions.

1. Do not even attempt to calculate a value for data sufficiency questions.

Data sufficiency questions take some getting used to. You are asked not to calculate a value but to determine whether you are able to do so with the information supplied. So abandon your computations the moment you realize whether you would (or would not) be able to complete them.

2. Do not shy away from C or E in data sufficiency problems because of the way they look.

Students display certain predictable behavioral weaknesses that the GMAT exploits. In data sufficiency, test takers may be reluctant to choose answer “C,” which typically states that both statements together are sufficient, but neither statement alone is—it seems too easy. Similarly answer “E,” stating that the question cannot be answered, feels like failure (it’s not), so candidates shy away from it. Be aware of these subconscious influences.

3. Do not overcalculate.

On quantitative questions that require a numerical answer, don’t waste time on elaborate computations. If your scratch paper is covered with numbers, you’re doing it wrong. Your ability to emulate a calculator is not what GMAT is interested in.

4. Determine the amount of calculation needed based on the answer choices.

If the question contains the word “approximately” or the answer choices are widely spread in value, GMAT is telling you that you should save some time by making approximations. Conversely, if the values of the answer choices are close together, this is sign that GMAT expects you to compute the answer precisely.

5. Stay away from the longhand approach. Take shortcuts: Plug in the answers and or eliminate them.

When it comes to problem solving, because the GMAT supplies five possible answer choices to each question, the task is not to calculate or derive an answer, but to choose one, a subtly different task. So in addition to the traditional analytical approach, there may be times when it’s quicker and more effective to adopt the numerical approach (also known as substitution, or “plugging in the answers”) or the logical approach (“which answers can I eliminate without calculation?”).

Too many test-takers use the dutiful, exhaustive, longhand approach. The GMAT doesn’t care about your process. So reserve some operational flexibility and be aware that there are three valid approaches to each math question in addition to various combinations of those three basic approaches.

Tracy Yun, who scored in the 99th percentile on the GMAT, is the co-author of Turbocharge Your GMAT. Yun is a Columbia Business School grad and is pursuing her passion for education after having spent years in investment banking as a merger-and-acquisition specialist, advising Fortune 500 companies on strategic investments.

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