Pi = 3.14159265358979323846…
It’s Pi (Approximation) Day today ( 22/7 ) first celebrated 20 years ago by Larry Shaw at the San Francisco Exploratorium. Pi or π is the mathematical constant which represents the ratio of any circle’s circumference to its diameter in Euclidean geometry—it’s also an irrational number (it cannot truly be expressed as a fraction, and its decimal representation never ends or repeats), as well as a transcendental number (no finite sequence of algebraic operations on integers [powers, roots, sums, etc.] can ever produce it). More on Pi here or here.
Happy Pi Day :-)