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Archive | GRE Arithmetic

GRE Math: Divisibility Rules

1. Which of the following is NOT divisible by 3? (A)  231 (B)  246 (C)  285 (D) 326 (E)  411 One way to do this problem is to divide each answer choice by 3 and see which one leaves a remainder. A far better approach, however, is to apply the following rule of divisibility for […]

Integers and Mental Math

What better way to spend the weekend than with your favorite friends: integers? Okay, maybe integers aren’t your best friends. But trust me, they are much better company than irrational numbers. Below are five problems dealing with integers and integer properties. They are definitely not too challenging. In fact, many can be solved using mental […]

GRE Math Basics: Least Common Multiple

If GRE math concepts were people, Least Common Multiple (LCM) would hardly be the most noticeable person in the room. After all, we have the really big personalities who always elbow for attention: Probability, Work Rates and Combinations (none of whom would win the popularity context). Then, there are Exponents standing together menacingly with Coordinate […]

It’s Not An Excited Number; It’s a Factorial!

If you’ve ever come across a number with an exclamation mark in front of it, that’s the factorial sign, e.g. 5!. Factorials don’t come up too often on the GRE, and when they do, it’s usually on harder problems. Still, you don’t want to be faced with an exclamation sign next to a number and […]

Think You Know Your Prime Factors?

Here is a good problem to test your understanding of prime factors, not to add multiples. See if you can finish the problem in less than 2 minutes. If P is the product of all of the positive multiples of 11 less than 100, then what is the sum of the distinct prime factors of […]