Five Strategies for Conquering 700 Level Quant Questions

Joe Lucero —  May 10, 2012 — 4 Comments

Let me start off by saying that hard work and mastering each question topic is the best way to conquer the GMAT. There is no Up-Up-Down-Down-Left-Right-Left-Right B, A, Start cheat code that can replace months of intense studying. That said, getting a 700+ score on the GMAT sometimes means having a few tricks up your sleeves. Here’s a few strategies that I’ve found to be helpful with gaining a few extra points at the very top of the GMAT curve:

1) Know your PEMDAS and your SADMEP

gmat quant stategy In other words, you have to know your parenthesis, exponents/roots, multiplication, division, addition, and subtraction, backwards and forwards. For as many students as I have worked with, I have yet to come across a student who can barely work through a multiplication table, yet still manages to consistently finish the quant portion of the GMAT. Even though you only need to answer 37 quantitative questions, this will entail hundreds of math calculations- calculations that far too many of us have left to the machines (I for one welcome our new calculator overlords). If the average straightforward calculation takes five seconds and a student sees two hundred of these calculations over an average test, that’s sixteen minutes and forty seconds of just doing simple arithmetic. And if it takes you twice as long to do each of those calculations, that’s going to take, umm, well, it’s…. it’s going to take a lot longer.

2) Small Numbers > Big Numbers

Not literally, of course. But when I see a 10! on the GMAT, I get excited. Not because the exclamation point tells me to, but because I know some poor student is going to spend a minute trying to multiply ten numbers together before realizing that he or she will nullify all that multiplication with a bunch of division. Meanwhile, I have cancelled out all sorts of numbers on the top and bottom of a fraction and have found that all but three (very simple) numbers are left to multiply. I wouldn’t convert my morning commute to inches in order to calculate my gas mileage, and I’m not going to multiply 725 so that I can divide it by 128. I’d rather let the two and threes on the top and bottom of this fraction fight it out and then deal with the survivors.

3) Impossible Numbers Are Numbers That Say I’m Possible

Students in my classes have often heard my impossible number problem rant. You’ve probably seen one of these types of questions yourself if you’ve taken a practice GMAT. A car manufacturer paints cars in the same order: red, blue, grey, pink, and black. What color will the 435th car be? And more importantly, what is a car manufacturer going to do with all those pink cars? Whenever I see an impossible number problem, I think to myself- if the GMAT thinks I can solve for the 435th car, it must think that I could somehow solve for the 435 millionth car and more importantly, the concept must not be that different from solving for the 5th car- in this case, each of these cars would be black. The size of the number is not what matters here, but the pattern that emerges from a problem does. Rather than starting at the largest number in the series and feel intimidated, think about how you would solve a simpler problem- what color would the fifth car be? Black. What other cars would be the same color? Car number 5, 10, 15, and so on. Now solving for car number 100 is no different than solving for car number 100,000.

4) Meet in the Middle

What’s worse than one scary equation? Two scary equations. Stop, take a deep breath, and remember again that if it’s on the GMAT, there must be some way to solve the problem. Unfortunately, you may not immediately recognize the trick that makes two equations and puts them in a similar form. But maybe you do recognize that you can FOIL the first equation and distribute some numbers from the second one. Get rid of an exponent here and reduce a fraction over there. A few modifications later and you now have two equations that look like one another but nothing like the equations that were originally given. Solutions aren’t always a one way street- sometimes your final answer will look nothing like anything the GMAT gave you.

5) Think About Extreme Scenarios

Not extreme like throwing your computer monitor across the room to see if you can get a retest because of a complete mental lapse. But when I see a Data Sufficiency question, one of the first questions I often ask myself is what would happen if I picked a preposterously large (or small) number. For example: let’s say that Alex and Brandon are driving in separate cars where Alex is driving 10 mph faster than Brandon. What if Brandon was traveling at 1 mph and Alex was traveling at 11mph? Alex is going 11 times as fast as Brandon. But if Brandon is traveling at 1,000,000 mph and Alex is cruising past him at 1,000,010 mph, that extra 10 mph doesn’t seem like all that much. In one case, the extra speed will save Alex hours of commuting time and in the other, the tiny extra boost is going to mean the same as a rounding error. The same thing often works when working with Variable-In-Choices (VIC) questions as well. Let’s say that a variable x represents how many minutes it takes for a copy machine to produce 100 pages and the question asks how many pages this machine could copy in 24 minutes. If I notice that in the five answer choices, sometimes the variable x is in the numerator and sometimes it is in the denominator, I can eliminate some of these answer choices immediately by thinking in extremes. If x = 1,000,000 then I’m dealing with an extraordinarily slow copy machine. Multiplying by a million would give me a very large answer and dividing by a million would give me a very small answer. So the correct answer choice needs to have the variable x in the denominator to show that this machine is not going to be able to make many copies in 24 minutes. Even if I’m only able to eliminate 2-3 answer choices this way, I’ve saved myself from having to do any calculations with those options.

Joe Lucero

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Joe Lucero has both a Biology degree and a Master of Education from the University of Notre Dame. He also has a 780 on his GMAT. In the fall, you will find Joe in a much better mood during weeks after the Fighting Irish win their football game. During the rest of the year, you will find him looking for new places to travel, reading almost anything non-fiction, crossfitting, and trying to solve every challenge problem in the Manhattan GMAT Student Center.

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