en.wikipedia.org/wiki/Pi

The number π is a **mathematical** constant. Originally defined as the ratio of a
circle's circumference to ...

www.math.utah.edu/~pa/math/pi.html

**pi**=3.14159 26535 89793 23846 26433 83279 50288 41971 69399 37510
58209 74944 59230 78164 06286 20899 86280 34825 34211 70679 82148
08651 ...

www.mathsisfun.com/numbers/pi.html

Draw a circle with a diameter (all the way across the circle) of 1. Then the
circumference (all the way around the circle) is 3.14159265... a number known as
**Pi**.

www.piday.org/million

Menu. **Pi** Day. Celebrate **Mathematics** on March 14th. 175 Days 17 Hours. Home
· Learn About **Pi** · Shop · Videos · News & Events · **Pi** Sightings · All Things **Pi**.

www.math.com/tables/constants/pi.htm

**Pi** is a name given to the ratio of the circumference of a circle to the diameter.
That means, for any circle, you can divide the circumference (the distance around
...

www.scientificamerican.com/article/what-is-pi-and-how-did-it

Regardless of the circle's size, this ratio will always equal **pi**. In decimal form ...
Additionally, **pi** shows up often unexpectedly in many **mathematical** situations.

encyclopedia2.thefreedictionary.com/Pie+(math)

**pi**,. in **mathematics**, the ratio of the circumference of a circle to its diameter. The
symbol for **pi** is π. The ratio is the same for all circles and is approximately 3.1416
...

www.livescience.com/29197-what-is-pi.html

Apr 30, 2013 **...** **Pi** (π), the 16th letter of the Greek alphabet, is used to represent the most widely
known **mathematical** constant. By definition, **pi** is the ratio of the ...