A Primer on Primes

A Primer on Primes

By: Rich Zwelling (Apex GMAT Instructor) Date: 30th March 2021 As I said in my previous post, GMAT Prime Numbers are my favorite topic. This is because not only are they inherently interesting mathematically but they show up in unexpected circumstances on GMAT...
Odds and Ends (…or Evens)

Odds and Ends (…or Evens)

By: Rich Zwelling, Apex GMAT Instructor Date: 18th March, 2021 Last time, we signed off with an Official Guide GMAT problem that provided a nice segue into Number Theory, specifically today’s topic of GMAT Odds and Evens. Now we’ll discuss the solution. Here’s the...
When Probability Meets Combinatorics: One Problem, Two Approaches

When Probability Meets Combinatorics: One Problem, Two Approaches

By: Rich Zwelling, Apex GMAT Instructor Date: 16th March, 2021 Now, we’d like to take a look at an Official GMAT Probability problem to pull everything together. The following is a good example for two reasons:  1. It illustrates a quirky case that is difficult more...