Last time, we talked about how to Test Cases on Data Sufficiency (DS) questions. ( If you haven’t read the first installment yet, go do that now. ) Today, you’re [...]

Welcome to the 3 rd and final installment of our mini-series on Number Properties. We’ve been doing a deep dive into Divisibility and Prime issues (see Part 1 and Part [...]

Welcome to the 2 nd installment of our dive into Number Properties. If you haven’t yet tried the first problem, start with the first article in the series . Let’s dive [...]

Most of my students are driven crazy by Number Properties. On the face of it, the topic seems straightforward: I know what positive and negative, odd and even are. Divisibility [...]

No introduction to this one—see what you can figure out and then we’ll talk about it! This is a GMATPrep® problem from the free exams. * “If n and y are [...]

We need to know a lot of different facts, rules, formulas, and techniques for the quant portion of the test, but there are 4 math strategies that can be used [...]

A certain class of questions tends to have more going on than might be apparent on the surface. (I’m being intentionally vague as to the “certain class” – I’ll tell [...]

Data Sufficiency problems often have elegant shortcuts if we really understand the theory behind whatever the problem tests – and, sometimes, DS sets up some very tricky traps if we [...]

How can the GMAT disguise a prime number (or any other) problem? I asked this question a couple of years ago at the start of a very important article entitled [...]

I don’t have a great title for you because I don’t have a really clean category for this question – and that’s exactly why it caught my attention and why [...]

What are number properties? This concept covers things that we often call “basic” – topics that we learned in middle school (or earlier): divisibility, factors and multiples, odds and evens, [...]

Today we’ve got an inequalities data sufficiency question on tap from GMATPrep®. Set your timer for 2 minutes and go! *Is m + z > 0? (1) m – 3 z [...]

Today we’re going to tackle a couple of tough divisibility problems from GMATPrep®. The two problems I’ve chosen share some interesting characteristics. Here’s your first one; set your timer for [...]

Here is a new Challenge Problem! If you want to win prizes, try entering our Challenge Problem Showdown . The more people that enter our challenge, the better the prizes! [...]

Here is a new Challenge Problem! If you want to win prizes, try entering our Challenge Problem Showdown . The more people that enter our challenge, the better the prizes! [...]

Here is a new Challenge Problem! If you want to win prizes, try entering our Challenge Problem Showdown . The more people that enter our challenge, the better the prizes! [...]

Here is a new Challenge Problem! If you want to win prizes, try entering our Challenge Problem Showdown . The more people that enter our challenge, the better the prizes! [...]

We’ve got another GMATPrep® word problem on tap for today, but this one’s in the area of divisibility (number properties). These kinds of problems often include a lot of math [...]

Here is a new Challenge Problem! If you want to win prizes, try entering our Challenge Problem Showdown . The more people that enter our challenge, the better the prizes! [...]

Here is a new Challenge Problem! If you want to win prizes, try entering our Challenge Problem Showdown . The more people that enter our challenge, the better the prizes! [...]

Here is a new Challenge Problem! If you want to win prizes, try entering our Challenge Problem Showdown . The more people that enter our challenge, the better the prizes! [...]

Here is a new Challenge Problem! If you want to win prizes, try entering our Challenge Problem Showdown . The more people that enter our challenge, the better the prizes! [...]

We'll give it to you straight: this strategy for finding the average, or arithmetic mean, of a set of numbers isn't for everyone. If you master it, though, you can [...]

You've heard of Autotune the News. But have you tried autotuning GMAT exponent rules? [youtube]http://www.youtube.com/watch?v=3wavlUC223E[/youtube] Dave Ingber (Knewton's lead GMAT teacher) and RoboMath (our lead GMAT robot?) show you how a little [...]

Here is a new Challenge Problem! If you want to win prizes, try entering our Challenge Problem Showdown . The more people enter our challenge, the better the prizes! Question [...]