# What’s the Origin of the Word “Pi”?

March 14 marks Pi Day, the holiday commemorating the mathematical constant π (pi), written numerically as 3.141592+. Since mathematic notation is a language that uses symbols from a multitude of alphabets and typefaces, it seems only fitting that this sixteenth letter of the Greek alphabet get a little attention.

The Latin name of the Greek letter π is pi, pronounced pie. The first recorded use of the letter as a mathematical symbol comes from the Welsh mathematician William Jones in a 1706 work called Synopsis Palmariorum in which he abbreviated periphery or its Greek ancestor περιϕέρεια, meaning “circumference,” to π.

The mathematical pi is defined as the ratio of the circumference of a circle to its diameter. As an irrational number, pi can never repeat when written in decimals; computers have calculated pi to decimal places in the trillions. It is also a transcendental number, a concept that exceeds the capacity of this post to explain.

Memorizing as many digits of pi as possible is an obsession for some. The Guinness World Record for memorizing digits of π is held by a man named Lu Chao. He set the record in November 2005 at Northwest A&F University in the Shaanxi province of China. It took him 24 hours and 4 minutes to recite the 67,890th decimal place of π without a mistake.

How will you celebrate Pi Day?