Pi, the Greek letter, from Phoenician, literally means "little mouth" and is the name of the mathematical constant, from 1841 in English, used in Latin in 1748 by Swiss mathematician Leonhard Euler (1707-1783), as an abbreviation of Greek *periphereia* "periphery."

Defined as the ratio of the circumference of a circle to its diameter, π, is an "irrational number," meaning its exact value is inherently unknowable. Pi is also a constant and appears everywhere there is a circle. Please do not have customers act as if they are pi, irrational and unknowable. Seek to understand your customers using all mathematical tools as possible. The circular economy is a good use of pi in the business world.

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Mouth of the river, meandering through forests, pi on the outside