# What is pi equal to?

1,061,967questions on

Pi or π is a constant whose value is the ratio of any given circle's circumference to its diameter.

It is approximately equal to 3.14159 in decimal.

There are also some exact representations of the value of pi:

• $\pi = \lim_{n \to \infty}\frac{P_{n}}{d}$ (Pi is the limit of the perimeter of a regular polygon with n sides as n reaches infinity divided by the intended diameter d - by Archimedes)
• $\pi = \frac{4}{1}-\frac{4}{3}+\frac{4}{5}-\frac{4}{7}+\frac{4}{9}-\frac{4}{11}\cdots.\!$ (Leibniz formula for pi)
 Includes CC-BY-SA content from Wikipedia's Pi article (authors)