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 Statue of Ahmes
If you divide the circumference of any circle by its diameter it yields a number that never ends or repeats.  This number is referred to as pi (B).  The circumference to diameter ratio (c/d) is a constant, no matter how large or small the circle.  This ratio produces is the number pi (22/7 or 3.1419…).   As early as the 2000 BC Babylonian mathematicians  used the ratio 25/8.   The Egyptian, Ahmes (1680-1620BC) also wrote about this relationship and came up with a value of 256 divided by 81  or 3.160.  Archimedes of  Syracuse discovered that pi is between 223/71  and 22/7, with the average being 3.1419.  He considered the perimeters of a 96 sided polygon and inscribed a circle with this polygon to determine approximation.   In 1768, Johann Lambert proved that pi has an infinite number of digits with a  repeating pattern.

Pi (B) has been found to be one of those numbers used in many other equations, to help determine unknowns.  It is easy to measure the diameter, but difficult to measure the circumference.  In a circle:  circumference =2Br;  area = Br2.  In a sphere:  surface area = 4 Br2; volume = 4/3B r3.

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