Learn about the definition of pi in relation to a circle with this BBC Bitesize Maths article. For students between the ages of 11 and 14.

In 1880, the German mathematician Ferdinand von Lindermann proved that pi is a transcendental number and that squaring a circle is impossible under the constraints of Euclidean geometry.

As we celebrate again in 2018, here are some Pi Day facts you should know. What Is Pi? Pi represents the ratio of a circle’s circumference to its diameter.

Known around the world as "Pi Day," it’s a time to celebrate one of mathematics' most famous constants: Pi, the ratio of a circle's circumference to its diameter, approximately 3.1415.