1. Pi is officially defined as the ratio of the circumference of a circle to its diameter. But don’t try to pin it down—its decimals go on forever and ever. Because of its handiness in formulas in fields from trigonometry to cosmology and biology, pi is the most commonly recognized constant in the math world. Nice!
2. The exact origin of its discovery is unknown, but may have arisen from a hunt led by the Babylonians. Or the Egyptians. Maybe Dennis Rodman was involved (read: no one really knows).
3. Its first 144 digits add up to 666—which Satanists claim is “the mark of the beast.” Spooky.
4. Appropriately, the yearly celebration of pi begins on 3/14 at 1:59 p.m. Sing it: Today we’re gonna’ party like it’s 3.14159.
5. Humans have been searching for the end of pi’s infinite digits for 3,500 years. It cannot be solved by computers. Apple be damned!
6. Albert Einstein was born on pi day: March 14, 1879.
7. It’s irrational (who isn’t?) and transcendental (jealous).
8. It’s been represented by the 16th letter of the Greek alphabet, “π,” since the 1700s. You also refer it by the fraction 22/7 if you want to be imprecise about the whole thing.
9. It shows up everywhere on the earth. Literally. We have pi in our eyes.
10. During O.J. Simpson’s murder trial, the judge and FBI agent tried to show off their smarts by debating the value of pi.
11. Some have given their lives in the name of pi. Archimedes, a brilliant mathematician in ancient Greece, spent his life trying to solve the ratio, only to be murdered by a Roman soldier while yelling “do not touch my circles.”
12. Its Greek symbol was suggested by English mathematician William Jones in 1706. He would have loved emojis.
13. Comedian John Evans once famously quipped: "What do you get when you divide the circumference of a jack-o'-lantern by its diameter? Pumpkin pi.” Mmm.
14. In 2010, Japanese system engineer Shigeru Kondo and U.S. computer whiz Alexander Yee broke the record for most digits of pi calculated, making it to five trillion decimal places using nothing but desktop computers, 20 external hard drives, and their freaking genius brains.
15. If trying to solve the ratio isn’t torture enough, you can join the millions of people who attempt to memorize it each year. Chinese math guru Lu Chao currently holds the Guinness World Record for most memorized digits. He dished out 67,890 in 24 hours and four minutes. Ow, his brain.
16. Today is one of the few days of the year that walking in circles is encouraged and eating pie in the early afternoon isn’t awkward.
17. Spoiler alert! The secret code in Alfred Hitchcock’s 1966 thriller Torn Curtain is pi.