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 ...

The number represented by pi (π) is used in calculations whenever something round (or nearly so) is involved, such as for circles, spheres, cylinders, cones and ellipses. Its value is necessary to ...

It is once again Pi Day (March 14—which is like the first digits of pi: 3 and 14). Before getting into this year's celebration of pi, let me just summarize some of the most important things about this ...