Search by birthday
Select your date of birth. We'll search for it in the first 10 million digits of π (loaded in chunks to keep memory low).
About π (Pi)
Simple explanation (for everyone)
π (pi) is the number you get when you divide the distance around any circle by the distance across it. If you measure around a pizza and across it, the ratio is always about 3.14 — that's π! It works for every circle, big or small.
What kind of number is π?
π is irrational: its decimal digits never end and never repeat. You cannot write it as a simple fraction. It's also transcendental, meaning it's not the solution to any ordinary polynomial equation with whole-number coefficients. Unlike numbers like ½ (0.5) or ⅓ (0.333…), π goes on forever with no pattern.
How many digits have been computed?
As of 2024, over 100 trillion decimal digits of π have been calculated (by 2022, Emma Haruka Iwao computed 100 trillion digits using Google Cloud). This app uses the first 10 million digits. Mathematicians have proven π's digits continue infinitely with no repeating pattern.
π in a circle
For any circle: C = π × d (circumference = π times diameter) and A = π × r² (area = π times radius squared). π appears in waves, physics, probability, and many areas of science and engineering.
Fun facts
- March 14 (3/14) is Pi Day.
- The sequence 123456 does not appear in the first million digits.
- Every possible finite sequence of digits is believed to appear somewhere in π (π is thought to be "normal").
- Ancient Babylonians approximated π as 3.125; Archimedes narrowed it to between 3.1408 and 3.1429.