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 ...

Learn these interesting facts about pi before Pi Day on March 14 Facts about pi you don’t want to miss How much do you really know about pi? Sure, you’ve heard about it in math class, but this famous ...