Fractional Focus, Exponential Improvement
(This is one of a series of GMAT tips that we offer on our blog.)
The very fact that the GMAT does not permit you to use a calculator should give you some insight in to the nature of the quantitative section’s emphasis – the GMAT is much less concerned with your ability to “crunch numbers” than it is with your logical skills, and the way in which you can make yourself more efficient while assessing and manipulating numbers.
Perhaps the best application of this insight is for you to focus on using fractions whenever possible – in lieu of either decimals or division problems. The GMAT almost exclusively features fractions that will ultimately reduce through calculation, whereas long division and/or the use of decimals will often waste quite a bit of your time and leave you prone to calculation errors simply because of the mass of digits you will need to carry.
Say, for example, you arrive at a calculation that requires you to divide 12 by 5. Rather than calculating that the answer will be 2.4, you’re best served to simply leave the number at 12/5, and wait to determine which step will be required next. The problem will likely take the form of the following:
A group of five children finds $12 on the playground, and decides to split it evenly between them. How much will each child have if the playground bully demands a 16.67% commission from each for allowing them to take the money inside?
While 12/5 is, indeed, 2.4, this problem is best calculated by keeping your fractions until the end. In this case, each child will receive 12/5, and be allowed to keep all but 1/6 of their amount (.1667 = 1/6). So, each child will keep 5/6 of 12/5.
This problem is relatively easy to solve: 5/6 * 12/5 allows you to cancel the fives in the numerator and denominator, and then divide the 12 by 6 to arrive cleanly at $2. By keeping your calculations in fraction form as long as you can, you’ll typically save yourself time and hassle, and can often perform the calculations mentally.
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