Pi is an important mathematical constant since it is the ratio of a circle's circumference to its diameter. The pi (π) is used in many mathematical formulae across math and physics. For the past ...

Pi, a mathematical constant denoted by the Greek letter π, is the ratio of a circle's circumference C to its diameter d: π = C/d. The circumference of a circle is, in turn, equal to 2πr, where r is ...

(NBC) - Happy Pi Day! The annual celebration, held every March 14, is your chance to pay tribute to the most famous constant in math and physics: the number you get when you divide the circumference ...