The definition of PI is "Greek letter" or "Ratio of circle's diameter to its circumference"
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The number π is a mathematical constant, the ratio of a circle's circumference to its diameter, approximately equal to 3.14159.
the number pi is a mathematical constant of a circle circumfference
and it is equal by 3.14159
pi is the ratio of the circumference of C of a circle to its diameter d,or c/d,and is apprximately equal to 3.1416...
The nbumber pi is aconstant of a circumference and it is equal by 3.14