Pi (π)

Pi (π) is a mathematical constant representing the ratio of a circle's circumference (the distance around it) to its diameter (the straight line passing through its center). This ratio is the same for all circles, approximately equal to 3.14159. Pi is an irrational number, meaning it cannot be exactly expressed as a simple fraction and its decimal expansion goes on infinitely without repeating. It is fundamental in geometry, especially when calculating areas and volumes of circular or spherical shapes. Pi appears in many formulas and fields, including mathematics, engineering, and physics.