Articles published in Quant

What Your Math Teacher Didn’t Tell You About PEMDAS

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Manhattan Prep GMAT Blog - What Your Math Teacher Didn't Tell You About PEMDAS by Chelsey Cooley

Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! Check out our upcoming courses here.


Here’s a phrase that might bring back some memories from middle school math class: Please Excuse My Dear Aunt Sally, or PEMDAS. (If you went to school outside of the U.S., you may have learned the acronym BEDMAS or BODMAS, instead.) You use this phrase to decide what order to do mathematical operations in: Parentheses first (from inside to outside), then Exponents, then Multiplication and Division (left to right), then Addition and Subtraction (also left to right).

PEMDAS isn’t terribly fancy stuff. It’s just a useful little tool that helps us communicate clearly—it’s what tells us, for instance, that “2x(3+4)” means something different from “2×3 + 4.” But if there’s one thing the GMAT loves, it’s making things look more complicated than they really are. Read more

FAST Math for the GMAT (Part 5 of 5)

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Manhattan Prep GMAT Blog - FAST Math for the GMAT (Part 5 of 5) by Stacey Koprince

Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! Check out our upcoming courses here.


Welcome to the fifth and final installment of our Fast Math series. (Miss any earlier ones? Start here.)

Make your life easier on the GMAT: do less Math. (Yes, with a capital-M. ) I use Math-with-a-capital-M to mean formal, textbook math.

Sure, you’re going to have to do some textbook math on the GMAT, but it’s really not a math test. Business schools don’t expect you to have to do paper math in b-school or the real world. Rather, they’re testing how you think about math. And thinking about math in the real world is a lot different than textbook, school-based math.

For one thing, the correct answer on the GMAT is never actually a number or a math term. The correct answer is just (A), (B), (C), (D), or (E). How you get to that correct letter doesn’t matter in the slightest.

Okay let’s dive into our 5th Principle for Fast Math! Read more

Un-Educated Guessing on the GMAT

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Manhattan Prep GMAT Blog - Un-Educated Guessing on the GMAT by James Brock

Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! Check out our upcoming courses here.


As any good GMAT student knows, you can’t possibly answer every question correctly. In fact, if you get the first couple questions right, you will rapidly get into territory where most people can hardly figure out what the questions mean. And if you take extra time to dig into those questions and try to figure them out, it bites you in a big way when you run out of time toward the end. So we quickly learn that if you can’t figure out a good plan to solve a problem, you need to go ahead and take an educated guess.

Sounds great, but it’s not actually that simple, is it? Read more

FAST Math for the GMAT (Part 4 of 5)

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Manhattan Prep GMAT Blog - FAST Math for the GMAT (Part 4 of 5) by Stacey Koprince

Guess what? You can attend the first session of any of our online or in-person GMAT courses absolutely free—we’re not kidding! Check out our upcoming courses here.


We’re up to part 4 of our series on Fast Math for the GMAT. If you’re seeing this for the first time, start with part 1 and work your way back here.

Let’s dive right in.

Principle #4: Estimate…and not just when they tell you to.

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How Many GMAT Problems Do I Need to Solve?

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Manhattan Prep GMAT Blog - How Many GMAT Problems Do I Need to Solve? by Chelsey Cooley

Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! Check out our upcoming courses here.


That’s a good question! Do you really need to solve all the GMAT problems in the Official Guide to the GMAT in order to score a 700? What about the other side of the issue: is it possible that there aren’t enough problems in the Official Guide? How many GMAT problems should you solve before taking the official GMAT?  

Before I share my answer, let’s get some facts on the table. Read more

FAST Math for the GMAT (Part 3 of 5)

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Manhattan Prep GMAT Blog - FAST Math for the GMAT (Part 3 of 5) by Stacey Koprince

Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! Check out our upcoming courses here.


Welcome to the third installment of our Fast Math series. (Miss the earlier installments? Start here.)

Here’s the basic premise: I’m always on the lookout for ways to get out of doing tedious paper calculations on the GMAT.

The awesome part: the test writers actually set this up for me! They know we’re not going to have to do a bunch of paper math in b-school or the real world, so they construct problems that allow us to take advantage of all sorts of shortcuts…if we’re paying attention. Read more

FAST Math for the GMAT (Part 2 of 5)

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Manhattan Prep GMAT Blog - FAST Math for the GMAT (Part 2 of 5) by Stacey Koprince

Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! Check out our upcoming courses here.


Welcome to part 2 of our Fast Math series! In Part 1, I acquainted you with the fact that I’m a lazy math person: I don’t want to do any more than I have to in order to answer the question. And this series shows you how!

Principle #2: Learn shortcuts for when you do have to do the math.

You already saw the first example of this in Principle #1:

Shortcut #1: When multiplying a string of numbers, pair off the 5’s and 2’s and multiply them first.

Let’s say that that problem hadn’t had a 20 in it. If we had to multiply 5 and 81…how would you do that? Read more

What’s the Deal with Square Roots on the GMAT?

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Manhattan Prep GMAT Blog - What's the Deal with Square Roots on the GMAT? by Chelsey Cooley

Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! Check out our upcoming courses here.


Here’s one of the most common math questions my students ask: “What’s up with negative numbers and square roots on the GMAT?” Luckily, the answer doesn’t involve a lot of complex rules. In this quick article, I’ll lay out the issues surrounding square roots and negative numbers, and share everything you need to know to handle them confidently.

If you’ve been studying for a while, or if you’ve worked your way through Foundations of Math, you probably know that there’s a strange interaction between negative numbers and exponents. If you square a negative number, the result is positive. If you square a positive number, the result is also positive. Squaring a number makes the negative sign ‘go away.’ This is where the problem with square roots comes in.

Suppose you’re looking at an equation that looks like this: Read more

FAST Math for the GMAT (Part 1 of 5)

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division-sign-gmat-fast-math-part-1-of-5-stacey-koprinceGuess what? You can attend the first session of any of our online or in-person GMAT courses absolutely free—we’re not kidding! Check out our upcoming courses here.


I don’t know about you, but I’m pretty lazy when it comes to doing math on paper. Blame constant access to Excel and the calculator on my phone…but I’m completely over doing math on paper.

If you give me a problem that’s going to require half a page of calculations…well, I’m not going to want to do that problem. But on the GMAT Quant section, I don’t get a calculator, so how can I still get a 99th percentile score while staying true to my lazy-math desires?

Let’s do some Fast Math! Read more

Error Log: The #1 Way to Raise Your GMAT Score!!

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Manhattan Prep GMAT Blog - The #1 Way to Raise Your GMAT Score: The Error Log!! by Elaine Loh

Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! Check out our upcoming courses here.


This is not hyperbole. I truly believe that the number one way to raise your score is to have a thorough error log. I have had a number of students who come to me after having gone through most of the Official Guide but who are still struggling to get the scores they want. When I ask, “What do you have to show for doing ALL of these problems?” the answer is often something along the lines of “I’m not sure.” That drives me bonkers! I want you to work smart, not hard.

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