Pi (π, the ratio of the circumference of a circle to its diameter), its older brother the golden ratio phi (φ) and the much younger e and i are the most famous numbers in mathematics. Pi is everywhere: not only in circles and spheres, but also in the results of all kinds of integrals, sums and products, as well as in number theory and physics. The personality of π is largely unknown: irrational, transcendental, possibly and probably normal.

Because of π’s importance, its digits (3.14159265…) have an almost cult following. The first few digits, 3.14, correspond to notation for March 14, which was first celebrated as Pi Day in 1988, in the San Francisco Exploratorium. Wolfram Research has the most π presence on the web, with material at the Wolfram Functions Site (pi page, pi visualizations), MathWorld (pi, circle, sphere) and the Wolfram Demonstrations Project (pi, circle, sphere, disk, wheel), not to mention several built-in Mathematica symbols (Pi, EllipticPi, PrimePi).

For NUMB3RS episode 314 (“Takeout”), we helped to fold many hidden π references into the script review and math notes. The writers, director, cast and crew added many more. The opening Black Box, for example: a 3-course meal, 1 restaurant, 4 robberies, 1592 death squad murders. Charlie mentions a circle-circle tangency joke not working, right before a James Bond reference (007—circle, circle, tangent).

Below are a few of our π-related Demonstrations. Click any of them to reach an interactive math demonstration. Enjoy!