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Pi

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.

To 100 Decimal Places

Here is Pi with the first 100 decimal places:

3.14159265358979323846264338327950288419716939937510 58209749445923078164062862089986280348253421170679...