what is pi?

Pi (written as the symbol π\pi π) is the number you get when you divide any circle’s circumference by its diameter, and it’s about 3.14159.

Quick Scoop

• Pi is a constant : for every perfect circle, big or small, circumference ÷ diameter is always π\pi π.

• Numerically, π≈3.14\pi \approx 3.14π≈3.14, but its exact decimal goes on forever without repeating, so it’s called an irrational number.

• It appears in many formulas, like:
  • Circumference of a circle: C=2πrC=2\pi rC=2πr.

* Area of a circle: A=πr2A=\pi r^2A=πr2.

• Pi shows up far beyond school geometry: in waves, oscillations, quantum physics, relativity, probability, and even signal processing.

• People celebrate “Pi Day” each year on March 14 (3/14), a now-classic geek-culture event with contests, puzzles, and of course, pie.

A tiny story-style picture

Imagine you wrap a string around any circular object—a coin, a pizza, a planet. Measure that string (the circumference), then measure the straight line across the middle (the diameter). No matter which circle you choose, if you divide the first length by the second, you always get the same mysterious number: a bit more than 3.14, and that number is π\pi π.

TL;DR: Pi is the never-ending number (about 3.14) that links every circle’s size to its edge, and it quietly powers a huge amount of modern math, science, and engineering.

Information gathered from public forums or data available on the internet and portrayed here.