π (sometimes written
pi) is a mathematical constant that is the ratio of any Euclidean circle's circumference to its diameter.Throughout the history of mathematics, there has been much effort to determine
π more accurately and to understand its nature; fascination with the number has even carried over into non-mathematical culture. Perhaps because of the simplicity of its definition,
π has become more entrenched in popular culture than almost any other mathematical concept, and is firm common ground between mathematicians and non-mathematicians. Reports on the latest, most-precise calculation of
π are common news items; the record as of October 2011 stands at 10 trillion decimal digits.
pi = 3.14159265
