It happens to everyone. (Sometimes even to GMATGurus, but let’s just keep that between us.) A seemingly strange or complex Problem Solving question hits the screen, and you think: I don’t know what to do.
The thing is, you’ve probably learned what to do. You’ve probably done it a hundred times before. So what you don’t want to do is sit there and stare. Or panic. Rereading the problem is certainly a good idea, but rereading it over and over—not so good. A wise motto to live by:
Your pen should always be moving.
When you’re stuck, here are some ways to unstick yourself so you can get that pen moving in the right direction:
Write down everything you know. The GMAT writers rarely include information you won’t need to answer the question. Write it all down. Sometimes just seeing all the information on your noteboard will help you to connect the dots. Ask yourself, why am I being given this information? How can it help me?
Figure out something small. Often figuring out something small will help you to figure out something big. Solving a math problem is like building a house. You lay each brick one at a time until you reach the roof. But it all starts with that first brick—that first small thing you figure out.
Look at the answer choices. Often the answer choices will point you in the right direction. Sqrt(2) should make you think: 45-45-90 triangle. Sqrt(3) should make you think: 30-60-90 triangle. If the answers are integers, maybe you could simply try each answer choice until you find the one that works. Let the answer choices help you.
Look at the numbers in the problem. If you see prime numbers, look for something to prime-factorize. If you see fractions, perhaps the correct answer will need to be divisible by all the denominators. Maybe by putting together the numbers in the problem with the numbers in the answer choices, you’ll be able to figure out what approach to take.
Ask yourself what’s being tested. What’s the problem about? Even versus odd? Combinations? A change in percentage? GMAT problems test algebra, geometry, statistics and number properties. No trig, no calculus. If you can figure out what’s being tested, maybe you can figure out the best approach.
Ask yourself what techniques might be useful. Can you plug in your own numbers? Can you plug in the answer choices? Can you translate the words on the screen into an equation on your noteboard? Ideally, you’ll walk into the GMAT having mastered many different approaches. If one doesn’t work, try another.
Guess and check. Try a value that you think might be correct. If it’s too big, try something smaller; if it’s too small, try something bigger. Keep trying values until you find the correct answer. Not the most elegant way to solve, but it’s better than just sitting there and staring — and more likely to lead to the correct answer.
Ballpark. The GMAT is a multiple-choice test. The answer choices often are far enough apart that a little estimating will allow you to choose the correct answer. In Problem Solving questions, figures are usually drawn to scale. If a circle inscribed in a square looks as though it’s taking up more than half the square, it probably is. Find the area of the square and estimate the size of the circle. (Just don’t use this approach in Data Sufficiency questions, which often include figures not drawn to scale.)
Eliminate traps. The goal of the GMAT writers is to create incorrect answer choices that will appeal to the average test-taker. Learn to recognize trap answer choices so that you can avoid them. If an answer choice reminds you of numbers in the problem, avoid that answer choice. Why? Because the average test-taker will be drawn to that answer choice, so it’s likely a trap. If the question asks for the largest possible value, avoid the largest answer choice. Why? Because the average test-taker will be drawn to that answer choice, so it’s likely a trap. And be forewarned: “It cannot be determined from the information given” is almost never correct. (Just because you can’t figure out the answer doesn’t mean it can’t be done.) By eliminating traps and ballparking, you can greatly increase your odds of choosing the correct answer—even when you don’t know how to solve the problem.
The key is to keep your pen moving. If one strategy doesn’t get you anywhere, try another. Yes, I know: each question is designed to be answered in approximately two minutes. But if you figure out how to solve the problem in front of you, you should take the time to answer it correctly. It doesn’t make sense to race to the next question, which you might have no clue how to approach. Just one caveat:
Recognize when to cut your losses. No question — not even the first — is worth 10 minutes of your time. Spend 10 minutes on one question, 8 on another, 7 on another, and you’ve just allowed three questions to consume 1/3 of your 75 minutes. Not the best approach if you want a good score. If after several minutes you still don’t know how to approach a question, you should eliminate traps, try to ballpark, guess, and move on. No single question is going to affect your score that much. And remember: about a quarter of the questions are experimental and don’t affect your score at all.
(Please note that the article above was not written with an eye toward the proper grammar that’s tested on the GMAT. Why? Because the goal of the article is not to test grammar but to impart information in — hopefully — an entertaining and readable way. If you spot a grammatical error, please feel free to point it out. The process might prove instructive to other readers.)