GMAT Tips: Quantitative Section (Math)

Related Topics:

Overall Tips for the GMAT Test

Overall Tips for the Test Day

Specific Tips for Essays or AWA section

Specific Tips for Verbal Section

Problem Solving Questions

• You will not need the keyboard for the Quantitative section, so move it aside to give you more desk room for writing on your scrap paper.
• Fortunately for you, advanced topics such as trigonometry and calculus are not tested on the GMAT. To score well, you only need to be familiar with high school-level arithmetic, geometry, and algebra.
• Read the questions carefully. The most common mistake GMAT test takers make is answering the question they thought they read, instead of the one the test actually asked. There is a big difference between a question asking, "Which of the following may be true?" and one asking "Which of the following may not be true?" The test writers deliberately include answer choices that correspond to misinterpretations of the questions.
• Use your scrap paper for every question. No matter how easy a question appears, you should write down your working. Seeing your working on paper will help you avoid easy mistakes and the answer choices designed to exploit them. Remember, once you answer a question on the GMAT, you can't go back and change it.
• Do not get bogged down with complicated or lengthy calculations. The GMAT problem solving questions should not require complicated calculations. If you find yourself getting stuck like this, you are missing a shortcut.
• The "guesstimating" technique is extremely effective on the GMAT. Most of the time, the answer to the question is a value, and the values given in the answer choices are not very close to each other. As a result, you can save time by 'guesstimating.' For example, if you know the value you're looking for is about 30%, and the answer choices are 4%, 13%, 29%, 47%, and 81%, you can safely guess that the correct answer is 29%. This saves you time and the chance of making an error in a long calculation.
• Learn how to work backwards. If you are completely stuck on a question, you can plug in an answer choice and work backwards to see if it makes sense. To save time, you are recommended to start with the middle value. Even if it does not answer the question, it might tell you if you need to go higher or lower. Then, you will have narrowed 5 choices down to 2.
• Convert quantities freely. If you can recognize relationships between the numbers in the problems, there is often a shortcut. Remember that the GMAT test writers do not haphazardly select numbers for their questions. This is especially useful in narrowing down answer choices when you feel the urge to pull out a calculator. One conversion to remember is that in the GMAT, π = 22/7.
• Use elimination as a last resort. The GMAT writers have historically arranged answer choices in ascending order. Even if you are unable to immediately home in on the correct answer, chances are that guesstimating, working backwards, or some other technique will help you eliminate many wrong choices.
• Practice, practice, practice. When you spend time practicing, you internalize these tips and strategies. You will also become comfortable with the type of questions found on this portion of the test, and will quickly realize whether you need to brush up your skills in any math areas. By test time, you should be able to recall certain information – the total number of degrees in the sides of a triangle, the formula for the area of a circle, etc. – off the top of your head.
• Assume diagrams are drawn accurately unless the question specifically states otherwise. Do not, however, rely on your visual judgment to answer these questions. It’s never that easy. One common mistake is to assume that 2 lines must form a right angle, when this is not stated anywhere in the text. Do not fall into this trap – it is one of the most common mistakes made on the GMAT.
• Spend at least 30 seconds reviewing the diagrams. Many facts can be drawn from the illustrations. You may need to copy the diagram on your scrap paper to dig up all these facts.
• Spend at least 30 seconds reviewing the graphs and tables. Graph problems are not supposed to require hard math calculations. Instead, they are supposed to test your ability to interpret and use graphs and tables. As a result, you should closely study the structure and basic content of the graphs and tables. The axis labels, legend key, and units of measurement are more important to you in understanding and answering the question than the actual data presented.
• Make sure you are familiar with bar, circle, and line graphs. These are the 3 graph types most commonly used on the GMAT.
• You can rely on visual estimates for bar graphs and line charts. The test writers will not use visual tricks on these questions. This will not work on geometry questions, however.
• Sometimes, you may encounter a problem that simply tests your reasoning skills, instead of your quantitative skills. These questions are widely considered the most intimidating on the entire exam. Learn to identify them. An example of this type of question is one that presents a function you never learned. You will improve your odds of answering the question correctly by following the ‘logic’ used. If this fails, you can always work backwards.
• Write equations for word problems. When solving a word question (such as what happens if trains are traveling at a certain speed), write an equation that will help you understand the question being asked and find the answer. Use obvious letter symbols to stand for the values you need to calculate.
• Don't waste time looking for hidden meanings in word problems.

Data Sufficiency Questions

• The data sufficiency section tests your ability to reason quantitatively, as opposed to your math skills. Therefore, it should not require lengthy calculation.
• The questions all have the exact same 5 answer choices. Memorizing them will save you time. They are as follows:

  A. Statement 1 alone is sufficient but statement 2 alone is not sufficient to answer the question asked.

  B. Statement 2 alone is sufficient but statement 1 alone is not sufficient to answer the question asked.

  C. Both statements 1 and 2 together are sufficient to answer the question but neither statement is sufficient alone.

  D. Each statement alone is sufficient to answer the question.

  E. Statements 1 and 2 are not sufficient to answer the question asked and additional data is needed to answer the question.

• Use elimination. If statement 1 is insufficient to answer the question, A and D can be eliminated. If statement 2 is insufficient, B and D can likewise be eliminated. If either statement is sufficient on its own, C and E are eliminated.
• Solve the problem systematically. A simple method is as follows:

1. Read the question carefully. Usually, the question asks for one of 3 things: 1) a specific value, 2) a range of numbers, or 3) a true/false value. Make sure you know what the question is asking.

2. Determine what information is needed to solve the problem. For example, to find out the area of a circle, you need to know the circle's diameter, radius, or circumference. Whether or not statements 1 and/or 2 provide that information will determine which answer you choose for a data sufficiency question about the area of a circle.

3. Look at each of the two statements independently of the other.

4. If step 3 does not give the answer, then combine the two statements. If the two statements combined can answer the question, then the answer is C. Otherwise, it is E.

• Use only the information given in the questions. Do not rely on a visual assessment of a diagram in a geometry question to determine angle sizes, parallel lines, etc. Nor should you carry any information over from one question to the next. Each question in the data sufficiency section stands on its own. You can count on finding wrong answer choices that take advantage of this mistake.
• The order in which you read the statements does not matter, as long as you read them separately. If you find statement 1 confusing, you can move on to statement 2 and see if it helps you eliminate wrong answer choices. This will save you time.
• Watch for statements that tell you the same thing in different words. When the two statements have the exact same information, the answer is either D or E. For example:

  1. x is 50% of y

  2. The ratio of y:x is 2:1

• Make real-world assumptions where necessary. You can assume that in abstract questions such as “What is the value of x?” with no clue as to what x represents (like most algebra questions) x may be a fraction or negative number.
• Practice makes perfect. With practice, you can internalize the above tips and strategies.