Pi (pronounced “pie”) is a mathematical constant equal to the ratio of a circle’s circumference to its diameter. That means for any circle, you can measure the circumference and divide it by the diameter and you will get Pi every time!

Pi is an irrational number, which means that it cannot be expressed by a simple fraction. The digits after the decimal will go on forever without repeating. The colourful web of smoke in the image above is actually a data visualization (created by mathematician Francisco Javier Aragón Artacho) representing 100 billion digits of the number Pi!

Math enthusiasts celebrate all things circular on Pi day—March 14 (3.14). If you’re going to celebrate Pi day with a pie, you can serve it on March 14 at 3:09pm + 26 seconds. Get it? 03/14 15:9:26 (maybe that's pushing it...).

If you prefer cake to pi(e), March 14 is also Albert Einstein’s birthday.

Pi has been recognized as a special number for a long time. Ancient people (Babylonians and Egyptians) started studying circles and their proportions nearly 4,000 years ago! They noticed that the circumference of a circle is always a little more than three times its diameter.

Archimedes (around 200 BC) was able to calculate Pi much more accurately. He started by drawing a hexagon inside a circle, and another hexagon outside the circle, and measuring the perimeters of the hexagons. For more about Archimedes method, check out Better Explained and Delphi for Fun

In recent years, Pi has been calculated to over one trillion digits! Don’t even try to memorize them all! However, you can remember the first few digits of Pi by counting the letters of the words in the phrase, “May I have a large container of coffee?” (3.1415926)

Hungry for more Pi?

Construct your own colourful representation of the number Pi with this fun and simple activity!

Survivors

Artist: Jeff Kulak

Jeff is a senior graphic designer at Science World. His illustration work has been published in the Walrus, The National Post, Reader’s Digest and Chickadee Magazine. He loves to make music, ride bikes, and spend time in the forest.

Egg BB

Artist: Jeff Kulak

Jeff is a senior graphic designer at Science World. His illustration work has been published in the Walrus, The National Post, Reader’s Digest and Chickadee Magazine. He loves to make music, ride bikes, and spend time in the forest.

Comet Crisp

Artist: Jeff Kulak

Jeff is a senior graphic designer at Science World. His illustration work has been published in the Walrus, The National Post, Reader’s Digest and Chickadee Magazine. He loves to make music, ride bikes, and spend time in the forest.

T-Rex and Baby

Artist: Michelle Yong

Michelle is a designer with a focus on creating joyful digital experiences! She enjoys exploring the potential forms that an idea can express itself in and helping then take shape.

Buddy the T-Rex

Artist: Michelle Yong

Michelle is a designer with a focus on creating joyful digital experiences! She enjoys exploring the potential forms that an idea can express itself in and helping then take shape.

Geodessy

Artist: Michelle Yong

Michelle is a designer with a focus on creating joyful digital experiences! She enjoys exploring the potential forms that an idea can express itself in and helping then take shape.

Science Buddies

Artist: Ty Dale

From Canada, Ty was born in Vancouver, British Columbia in 1993. From his chaotic workspace he draws in several different illustrative styles with thick outlines, bold colours and quirky-child like drawings. Ty distils the world around him into its basic geometry, prompting us to look at the mundane in a different way.

Western Dinosaur

Artist: Ty Dale

From Canada, Ty was born in Vancouver, British Columbia in 1993. From his chaotic workspace he draws in several different illustrative styles with thick outlines, bold colours and quirky-child like drawings. Ty distils the world around him into its basic geometry, prompting us to look at the mundane in a different way.