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Finding the Counterfeit Coin

Mar 31, 2014

I wrote about a brain teaser I encountered as a kid and challenged you to figure out if it has a solution, and if so, what that solution is. That brain teaser works like this: You have 12 identical coins. One of them is counterfeit. The counterfeit coin may be heavier...

The Toughest Brain Teaser

Sep 19, 2012

People seem to like the brain teasers I’ve posted.  So here’s another. I first ran across this when I was about 12 years old.  I still remember it as one of the toughest brain teasers I ever faced. It is a very simple problem to explain, but the answer...

Pythagorean Triplets and Diophantine Equations

Jul 16, 2012

Last week I posed a challenge that came from my high school computer teacher: Can you find an efficient method (or “algorithm”) to generate Pythagorean triplets? As a reminder, a Pythagorean triplet is a set of three integers that satisfy the Pythagorean...

Brain Teaser: Finding Pythagorean Triplets

Jul 9, 2012

In an earlier post I wrote about a brain teaser from middle school.  Here’s one that is a bit more advanced. My high school computer teacher issued us a challenge: “I want you to write an algorithm to identify Pythagorean triplets.” At the time, I...

Brain Teaser: Proof That 2 = 1

Jun 29, 2012

This is a classic brain teaser I learned in middle school (or “junior high school” where I grew up). Let’s prove that:  Here’s the proof: Let’s start by establishing some variables: Okay, so if that’s true, then we know:  In...