This number, approximately 1.62, has fascinated mathematicians and artists for centuries—but perhaps not for the reasons you think.

Etch A Sketch Calculus Video Gets Kid Into MIT

Iowa teen Dezell Turner's hobby gave this college applications a ser…

Solution to Riddle of the Week #55

Difficulty level: Hard

Riddle of the Week #55

Difficulty level: Hard

The Hardest Logic Puzzle Ever

Difficulty level: Hardest Ever

Solution to Riddle of the Week #54: The Hardest Logic Puzzle Ever

Difficulty level: Hardest Ever

Riddle of the Week #53: Knights and Knaves, Part 11

Difficulty level: Hard

Solution to Riddle of the Week #53: Knights and Knaves, Part 11

Difficulty level: Hard

Pi Makes Perfect Sense in These Simple Animations

We all know pi is (roughly) 3.14, but where did that number come from?

The "Müller-Lyer Pulsating Star" Is Our New Favorite Optical Illusion

The line segments are the same length. Really.

Solution to Riddle of the Week #52: Knights and Knaves, Part 10

Difficulty level: Hard

Riddle of the Week #52: Knights and Knaves, Part 10

Difficulty level: Hard

Riddle of the Week #51: Knights and Knaves, Part 9

Difficulty level: Very Hard

Solution to Riddle of the Week #51: Knights and Knaves, Part 9

Difficulty level: Very Hard

Why Aren't Helicopters Faster?

How physics explains why the fastest car is faster than the fastest helicopter.

The Equation That Produces a Graph of Itself

Tupper’s Self-Referential Formula describes itself, along with pretty much everything else.

Solution to Riddle of the Week #50: Knights and Knaves, Part 8

Difficulty level: Hard

Riddle of the Week #50: Knights and Knaves, Part 8

Difficulty level: Hard

Solution to Riddle of the Week #49: Knights and Knaves, Part 7

Difficulty level: Moderate

Riddle of the Week #49: Knights and Knaves, Part 7

Difficulty level: Moderate

Riddle of the Week #48: Knights and Knaves, Part 6

Difficulty level: Moderate

Solution to Riddle of the Week #48: Knights and Knaves, Part 6

Difficulty level: Moderate

Math Shows Why Speeding Is So Dangerous

A small change in speed can dramatically increase the energy of a collision.

Riddle of the Week #47: Knights and Knaves, Part 5

Difficulty level: Moderate

Solution to Riddle of the Week #47: Knights and Knaves, Part 5

Difficulty level: Moderate

Solution to Riddle of the Week #46: Knights and Knaves, Part 4

Difficulty level: Moderate

Riddle of the Week #46: Knights and Knaves, Part 4

Difficulty level: Moderate

Solution to Riddle of the Week #45: Knights and Knaves, Part 3

Difficulty level: Moderate

Riddle of the Week #45: Knights and Knaves, Part 3

Difficulty level: Moderate

How to Cheat at 'Settlers of Catan' and Never Get Caught

Probability makes this cheat impossible to detect, not that you should do it or anything.