GMAT Tip of the Week: Don't Just Stand There...

Welcome back to Hip Hop Month in the GMAT Tip of the Week space, where this week we’re taking it old school with a GMAT Quant lesson courtesy of the much-karaoked (and poorly Weird Al Yankoviced as you’ll see below) Young MC:

This here’s a post for all the students
Trying to finish the quant section with wit and prudence
But waste a lot of time ’cause they’re overzealous
Question’s too abstract is what they tell us

More quant section, another tough question
Full of classic GMAT misdirection
You need to post a score of which schools will approve
(Everybody now…)
So don’t just stand there, bust a move

In his much-better-written version of the classic Bust A Move, Young MC’s advice to all the lovesick fellas is similar to the advice that Wayne Gretzky gives aspiring hockey stars – you miss 100% of the shots you don’t take. In order to have any success, you can’t just stand there, you need to bust a move.

In perhaps no venue is this more apt than on the GMAT quant section, in which many questions are presented in deliberately abstract ways to confuse and intimidate the weak of spirit. The secret to success? The GMAT helps those who help themselves – just get started, or in other words bust a move. Nearly all questions will contain multiple unknowns…but they will all contain “knowns”, too. And the key to success is starting with what you know instead of worrying about what you don’t. Consider the question:

If the symbols ∆ and ◊ each represent digits in the following subtraction operation, what is the value of ◊?

∆◊◊
-∆∆
667

(A) 3
(B) 4
(C) 5
(D) 8
(E) 9

This question looks like few others you’ve seen – there are variables, but they’re not letters and they represent digits, not numbers. So it’s like algebra, but it’s not really algebra. As Young MC might say…first frustration, next inclination is to just pick C and leave the situation but every dark tunnel has a light of hope so don’t hang yourself with the <600 rope. What do you do? Bust a move - think about what you DO know and start from there. And what you DO know is probably more than you think.

You have a three-digit number and you’re subtracting a two-digit number (so a number between 10 and 99). And the result is 667, or more generally “in the mid 600s”. That should help quite a bit – obviously you cannot start with a number in the 500s, take something away from it, and end up with a number in the 600s. So ∆ MUST BE 6 or greater. Then think about the flip side – if you take the smallest three-digit number that begins with 8 (800) and subtract the largest possible two-digit number (99), you still can’t get low enough to be in the 600s: 800 – 99 is 701, which is too big. So ∆ CANNOT BE 8 or more. ∆ has to be either 6 or 7. And with only two choices there, you’re in trial/error territory if you want to be.

So think about a ∆ of 6. That means that ∆◊◊ – ∆∆ is really 6◊◊ – 66. And again you can play min/max here – even if the three-digit number was the biggest it could be while starting with 6 (699), if you subtract 66 from it you end up with 633 – still too small to equal the 667 that we know we have to reach. So ∆ CANNOT be 6 – it MUST BE 7. Which leaves you with:

7◊◊
-77
667

Now it’s just an algebra problem. 667 + 77 = 744, meaning that the answer is 4. And more importantly to your study is this takeaway – on abstract quant problems, the single biggest key is to to just get started by taking inventory of what you know. In other words, don’t just stand there…bust a move. Those who just stand there waste valuable time and confidence, arguably the two most important test-day resources that you can control once you reach the test center. But those who embrace the “bust a move” mentality are rewarded handsomely, as they often find that the questions themselves are much more manageable than they look at first glance. The GMAT loves to throw deception at you in the form of abstraction and large or weird numbers, but in doing so it rewards those who confidently begin making sense of the awkwardness presented to them.

Getting ready to take the GMAT soon? On March 21 we will run a free live online seminar to help you get up to speed on the new Integrated Reasoning section coming in June. And, as always, be sure to find us on Facebook and Google+, and follow us on Twitter!

One Response

  1. Carcass says:

    this is one of that question if you think upfront about your strategy you will be reward. for me at first look is tough, not really, but tough.

    Following back solve: the rhombus symbol is equal so can be 33 44 55 88 or 99. Assume that is 33 and from here move to evaluate the choices. Now, we have as a result 667, as a consequence our first number should be 700 or something like that so: 744 – 77 = 656 does not work. B 744 – 77 = 667. Bingo.

    In one minute or less. Hope this helps someone :)

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