Pi Day Celebrates Mysterious Number Whose Digits Stretch to Trillions

Pi Day on 3/14 celebrates pi, which is the ratio of a circle's circumference to its diameter. Pi is an irrational number, meaning its digits go on forever without repeating.

The record for most decimal places of pi memorized is 70,000. There are techniques like Pilish (poems matching pi's digits) to remember all those digits.

In 2021, researchers calculated pi to 62.8 trillion decimal places, far beyond the previous record. Yet NASA only uses the first 16 digits for most calculations.

Ancient civilizations estimated pi as early as 1900 BC. But it wasn't until 1706 that William Jones introduced the Greek letter π as a shorthand symbol to represent it.

We still don't know if pi is a "normal" number where digits appear randomly. After 2.24 trillion digits, pi seems normal so far, but more analysis is needed.