In 2012, the educational website Khan Academy began accepting answers expressed in terms of . The constant is made available in the Google calculator and in several programming languages such as Python, Raku, Processing, Nim, Rust, Java, .NET, and Haskell. It has also been used in at least one mathematical research article, authored by the -promoter Peter Harremoës. The following table shows how various identities appear if was used instead of . For a more complete list, see List of formulae involving . Examples of use As an angular unit, the turn is particularly useful in many applications, such as in connection with electromagnetic coils and rotating objects. See also Winding number. Pie charts illustrate proportions of a whole as fractions of a turn. Each one percent is shown as an angle of one centiturn. See also Ampere-turn Hertz (modern) or Cycle per second (older) Angle of rotation Revolutions per minute Repeating circle Spat (angular unit) – the solid angle counterpart of the turn, equivalent to steradians. Unit interval Divine Proportions: Rational Trigonometry to Universal Geometry Modulo operation Twist (mathematics) References External links Tau manifesto Units of plane angle Mathematical concepts 1 (number)