The mathematically inclined will appreciate this graphic expression of the number Pi as the number 3.14159... Pi is a constant irrational, that is a constant that can be used to represent the ratio of any circle's circumference to its diameter in Euclidean geometry, which is the same as the ratio of a circle's area to the square of its radius. Being irrational, the decimal expansion never repeats or ends so the numbers on this Pi jumbo pencil keep going. Pi is used extensively in mathematical, science and engineering applications. Please allow us to chose a color for you! Designed exclusively for HMNS.