Pi

The ratio of any circle's circumference to its diameter — the most recognizable constant in mathematics.

Specifications & Metrics

symbol

π

approx

3.14159265358979…

Core Principles & Analysis

• Lambert proved π irrational in 1761; Lindemann proved it transcendental in 1882.
• Both properties together make squaring the circle with compass and straightedge impossible.
• The symbol π was popularized by Euler in 1737, from Welsh mathematician William Jones's 1706 usage.