## GMAT Official Guide 2020 – Data Sufficiency Question #424 Solution

Data Sufficiency questions can be challenging to get your mind around on the GMAT under the best of circumstances, and they’re made even harder when they combine a number of different elements and nuances that make determining sufficiency even more difficult. Question #424 from the GMAT Official Guide 2020 is one of those questions that […]

## GMAT Algebra Shortcut – GMAT Official Guide 2020 PS #207

One of the more challenging GMAT algebra questions from the GMAT Official Guide 2020 is question #207. My students often ask me about it so my guess is that you could use some help with it, too. Here is a video answer explanation breaking it down for you step-by-step. In it I take a non-standard […]

## GMAT Primes and the “Magic” of the Number 2

Numbers play an important role on the quantitative section of the GMAT, for obvious reasons, and arguably the most important numbers tested are prime numbers. As a reminder, a prime number is any number whose only two factors are 1 and itself. The first ten prime numbers, which you should know for the GMAT, are […]

## Understanding Pi on the GMAT – Happy Pi Day!

It’s Pi Day, March 14th (3.14)! In celebration, I want to share a quick mindset about Pi that I think you’ll find really helpful. I had a student ask me recently how to “solve for pi” in GMAT geometry questions. We went back and forth and it turns out she was really confused about the concept […]

## GMAT Interest Rate Problems – Part 2: Compound Interest

In “GMAT Interest Rate Problems – Part 1” we looked at simple interest and the way it’s commonly tested on the GMAT. What makes it “simple” is the fact that interest is accrued over one (1) time period, generally one year. If you invest $5,000 and earn an interest rate of 5%, it’s assumed that […]

## GMAT Interest Rate Problems – Part 1: Simple Interest

Picture this: You go to the bank and open a savings account. They offer you a CD with an interest rate of 5% (not likely in today’s market, but stick with me here). You deposit $5,000 into that CD. Question: How much money will you have at the end of the year? Pretty simple, right? […]

## GMAT Number Theory: How to Reason Your Way to a Right Answer

The GMAT is a reasoning test. It’s not a math test. It’s not an English grammar test. It’s not a writing test. Sure, there are elements of all of that in the questions you have to answer. But ultimately, the GMAT is a reasoning test. For proof, look no further than the names of the […]

## Solving GMAT Factorials

GMAT problem solving questions that contain the words “How many ways…?” may land you in a situation where you have to deal with factorials. Of course, we have useful strategies for getting certain of these types of questions right without resorting to combinatorics. However, sometimes the fastest and easiest way to answer these questions is […]

## The Art of Transformation on GMAT Algebra Questions

GMAT Math Tip: Start With the End in Mind Sometimes we overcomplicate GMAT algebra questions. Actually, let me rephrase that. Sometimes we see what looks to be a challenging GMAT algebra question, we freak out, we convince ourselves that we don’t even know where to begin, and we all but throw in the towel. Ever been […]

## GMAT Probability – Addition Rule Nuance

Pay Attention to Mutually Exclusive Events Pretty much all probability questions on the GMAT can be answered using three core rules. We teach them in detail in our Probability and Combinatorics course, but I want to take a second to tease out an important nuance to the Addition Rule (officially known as the “Union” rule) […]