Every year on 14 March, math lovers around the world celebrate Pi Day—a playful tribute to the mathematical constant π (pi). The date works perfectly in the month/day format because 3/14 matches the first three digits of π: 3.14.
What Is Pi?
Pi is the number that describes the relationship between a circle’s circumference (the distance around it) and its diameter (the distance across it). No matter how large or small the circle is, the ratio is always the same: π. What makes π especially fascinating is that it is irrational, meaning its digits never end and never repeat in a predictable pattern. Mathematicians have calculated trillions of digits, yet the number continues endlessly.
A 4,000-Year Quest for Pi
People have been trying to calculate π for nearly 4,000 years. Ancient Babylonians estimated π at about 3, later refining it to 3.125. The Egyptians, using formulas recorded in the Rhind Papyrus, arrived at a value close to 3.1605.
The Greek mathematician Archimedes made one of the first systematic attempts to approximate π. By calculating the areas of polygons inside and outside a circle, he determined that π lies between 3 1/7 and 3 10/71.
Centuries later, Chinese mathematician Zu Chongzhi used an astonishingly precise method involving a polygon with 24,576 sides to calculate π as 355/113, an incredibly accurate approximation for its time.
The symbol π itself was introduced by William Jones in 1706 and later popularized by mathematician Leonhard Euler.
Discover Pi at the ORL
Whether you enjoy puzzles, science history, or hands-on learning, the ORL’s collection offers plenty of ways to explore the wonders of mathematics.
In Happy Pi-Day to You! All About Measuring Circles, Bonnie Worth’s Cat in the Hat introduces Sally and Dick to the math behind Pi Day, turning circles, measurements, and the number π into a playful learning adventure.
In Humble Pi: When Math Goes Wrong in the Real World, mathematician Matt Parker explores real-life mathematical blunders—from internet glitches to engineering mishaps—revealing how small calculation errors can lead to surprisingly big consequences.
In Sir Cumference and the Dragon of Pi, Cindy Neuschwander blends math and adventure as young Radius searches for the magical number π to save his father from a potion that has transformed him into a dragon.
However you celebrate—reading about math, baking a pie, or writing a π-ku—we hope Pi Day inspires a little curiosity and a lot of learning!
Need More Help?
Call us at 1-844-649-8127 or email help@orl.bc.ca. Please include as many details as you can about your question, account, or device. This helps us support you more quickly and accurately.
Library card expired? Reach out to your local branch or contact us online to renew—it’s quick and easy.
