Pi

Pi is a math constant that represents the ratio of a circle's circumference to its diameter. This irrational number, approximated as 3.14159, has many uses across science and mathematics. Pi's decimal representation is infinite and patternless, making it an intriguing focus of study. From estimating spherical volumes to modeling wave patterns, pi's applications span geometry, physics, engineering and more. Its ubiquity speaks to pi's fundamental role in relating a shape's curved boundary to the space it encloses. Though easy to state, pi conceals an endlessly complex internal logic that has captivated great minds for millennia.