1. People Have Been Using Pi for Thousands of Years
Pi (the Greek letter π, pronounced like the word “pie”) is the ratio of the circumference of any circle to the diameter of that circle, explains math instructor Steven Bogart in Scientific American. It equals roughly 3.14. No matter what size a circle is, the circumference will always be 3.14 times bigger than the diameter.
Over 4,000 years ago, the ancient Egyptians and Babylonians had figured out this constant and were using it to make calculations. In the 18th century, mathematicians gave the number the name “pi.”