The Cognitive Economy
01/08/2014 12:00 Indexed under: 0_about-this-index
The number π is a mathematical constant, the ratio of a circle's circumference to its diameter, commonly approximated as 3.14159. It has been represented by the Greek letter "π" since the mid-18th century, though it is also sometimes spelled out as "pi" (/paɪ/). Source: Wikipedia.