The sixteenth letter of the Greek alphabet, which in mathematics stands for a transcendental number, approximately 3.14, which expresses the ratio of the circumference to the diameter of a circle and appears as a constant in many mathematical expressions. If you need it carried a few places further to the right [quite unlikely actually, but just in case, here are 52]: pi = 3.14159265358979323846264338327950288419716939937511 2 pi = 6.283185306 Pi squared = 9.86960440108935861883 The square root of pi = 1.772453851 In China, pi is a bee which symbolizes heaven; a jade disk.