Pi
Pi, or π, is the ratio between the circumference and the diameter of a circle. The numerical value of π depends on context: which circle is under consideration, and how precise are one's measurements?
The traditional concept
Standard mathematics says that π is the ratio between the circumference and the diameter of a perfect circle.
Standard mathematics "measures" this ratio using the methods of calculus.
Standard mathematics' notion of π is an irrational number---a number which cannot be written as a ratio of two whole numbers.
Thus in standard mathematics,
π = 3.141592653589793238462643383279502884197169399375105 8209749445923078164062862089986280348253421170679...
where the "..." signifies that the digits go on forever.
delete me
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