Calculator Independence Day

(This is one of a series of GMAT tips that we offer on our blog.)

Today marks the office-closure observance of the American Independence Day (which officially takes place tomorrow, July 4). Independence in any context can be both daunting and freeing; for a fledgling nation, freedom from taxes may be exciting, but the need for self-government can be troublesome (as the Articles of Confederation demonstrate). For a young adult, the freedom from parental control may be liberating, but all the while the financial independence can be more difficult than expected.

For a GMAT test-taker, often the “independence” from a calculator is viewed as more intimidating than liberating. For many of us, addiction to calculators and Microsoft Excel makes calculation by hand a lost art. However, as you prepare for the GMAT, you should note that the GMAT’s prohibition on calculators can be a distinct advantage for you.

Keep in mind that b-schools will allow you (or even require you) to use financial calculators and advanced spreadsheet programs. They don’t care much whether you can grind out lengthy calculations by hand; instead, they want to see how you can efficiently solve problems. For that reason, you should consider number properties and estimates whenever you see a problem that would otherwise cost you extensive time in performing the calculation. Consider a problem such as:

What is the square root of 1369?

A) 32

B) 34

C) 36

D) 37

E) 43

Squaring each of the answer choice digits could take extensive time, and need not be done. Because only an odd number multiplied by itself could give us an odd product (even * even will always be even), the only plausible choices are 37 and 43. Then, to determine which of 37 and 43 could be the correct answer (each would yield a unit’s digit of 9 when squared…we’ll cover that strategy in a future Tip of the Week post), we can estimate: 40^2 should be easy to calculate, as it’s simply 4^2 followed by two zeroes, or 1600. Because 43^2 would be greater than 40^2, the only plausible choice is 37.

When a calculation looks to be too difficult or time-consuming, it probably is, at least for the purposes of the GMAT. Let your independence from calculators be your guide whenever possible, and rely on your problem solving abilities to help you find an easier way.

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