# Pi

Updated: 10/17/2017 by Computer Hope

**Pi** may refer to any of the following:

1. The mathematical constant **pi** (the Greek lowercase letter **π**) equals the ratio of a circle's circumference to its diameter. It is an irrational number, whose value to twenty-four digits is 3.14159265358979323846264.

To insert the pi symbol in a web page, use the extended HTML (hypertext markup language) code **π**.

Tip

The unofficial **Pi day** is celebrated March 14th of every year, which is 3/14 or the first three digits of pi.

Tip

In Windows, to insert a pi symbol, open the character map tool. Select and copy the mark to be inserted into any document or picture.

2. Pi is also the symbol for a **Pebi**.