There aren’t many constants in Life, but you can always count on Pi. Today is the 24th annual celebration of that wonderfully useful yet completely irrational number…Pi.

Although the Greek letter has been around since…well…ancient Greece, the number was first named Pi by the mathematician William Jones in 1706. He used it as an abbreviation for “periphery/diameter”. Before this, good old Pi was known as **Archimedes’ Constant**.

Pi is an irrational number, which means that its value cannot be expressed exactly as a fraction having integers in both the numerator and denominator. With it you can figure out the diameter and area of a circle. Without Pi we wouldn’t have wheels or gears or PIE! On second thought , we’d probably still have Pie.

Many people celebrate Pi Day by competing to see who has memorized the most digits. Akira Haraguchi, has claimed he has memorized 100,00 digits but this has not been confirmed by the Guinness Book of Records. The Guinness-recognized record for remembered digits of π is 67,890 digits, held by Lu Chao, a 24-year-old graduate student from China.It took him 24 hours and 4 minutes to recite to the 67,890th decimal place of π without an error. **If you want to memorize Pi, click here to see Pi rendered to a million digits.** Get cracking.

You can also celebrate the day by baking a Pi Pie. Many Pi-philes will gather to form huge human Pis.

If you missed this year’s celebration you can gear up for Pi

Approximation Day on July 22nd.