Pi
 | Pi (the symbol is the Greek letter π) is: The ratio of the Circumference
to the Diameter
of a Circle. |  |
In other words, if you measure the circumference, and then divide by the diameter of the circle you get the number π It is approximately equal to: 3.14159265358979323846… The digits go on and on with no pattern. In fact, pi has been calculated to over one million decimal places and still there is no pattern. |
Approximation
A quick and easy approximation to Pi is 22/7
22/7 = 3.1428571...
But as you can see, 22/7 is not exactly right. In fact Pi is not equal to the ratio of any two numbers, which makes it an irrational number.
