37 questions must be answered in 75 minutes – approximately 2 minutes per question – in the GMAT math section. Under such time pressure, calculation accuracy and speed are crucial. However gaining accuracy and speed requires patience and consistent practice throughout the course of your GMAT preparation. And the proper way to practice is to concentrate on accuracy first. You can also use your favorite graphing calculator to practice. If you do not have one, read my graphing calculator reviews here.
That means in the beginning, do not focus on the time it takes to finish any question, focus on the correctness of your answer and the level of confidence you have in your answer. Once you’re more comfortable with the numbers, the operations, and the underlying math concepts, you will then be ready to pick up some speed. Here are a few tips that helped many of my previous readers/students.
Accuracy Boosting Tips
Copy the exact equation/expression
This seems obvious, but I have seen many students miswrite numbers, names of variables, and even operation signs (i.e. “+” instead of “-“) when they copy equations/expressions from the original question and from the previous step of their calculations. Making this mistake is fatal.
Do NOT do calculations in your head
If you don’t know what 12 x 14 is, work it out using long multiplication. Is 1/32 greater than or less than 0.32? Divide 1 by 32 using long division, then compare.
Show all work
When dealing with algebraic expressions, the marginal time saved from skipping steps can cost you more time when you need to go back to check what went wrong. In the worst case, your wrong answer matches a trap answer in the answer choices. Always write out each step of your work.
Learn from your own mistakes
Check for calculation errors when you get a question wrong. Pay very close attention to them because those are the mistakes you are likely to commit again.
Fine-tuning Calculation Tips
Cross cancel common factors before multiplying fractions
The optimal way of performing fraction multiplication is to cross-cancel any common factors between the numerators and denominators before multiplying them. For example, know the common decimals/fractions conversions. Expect to see these numbers in the real exam. Knowing their conversions as facts rather than calculations can save you precious seconds.
Import powers of numbers
Suppose the square of a hypotenuse you computed is 196. Then what is the hypotenuse? If you had memorized this list of common powers of numbers, you would know the answer in a blink of an eye.
Keep on practicing this because you can save noticeable time – anywhere from 20 seconds to 1 minute – if you can do them fast.
Any time a question, usually a number property one, asks about divisibility or factors, breaking down numbers into prime factors should first come to mind. First practice prime factorization using a prime factor tree. Once you’re familiar with the process, then leverage your knowledge of the powers of numbers that you memorized.
Consistent practice makes perfect. Always remember: accuracy comes first, the speed follows. Good luck everyone!