The earliest known use of the Greek letter ПЂ to represent the ratio of a circle's circumference to its diameter was by the Welsh mathematician William Jones in 1706. The first computational formula for ПЂ, based on infinite series, was discovered a millennium later. In the 5th century AD, Chinese mathematicians approximated ПЂ to seven digits, while Indian mathematicians made a five-digit approximation, both using geometrical techniques. Around 250 BC, the Greek mathematician Archimedes created an algorithm to approximate ПЂ with arbitrary accuracy. Ancient civilizations, including the Egyptians and Babylonians, required fairly accurate approximations of ПЂ for practical computations. The decimal digits of ПЂ appear to be randomly distributed, but no proof of this conjecture has been found.ДЇor thousands of years, mathematicians have attempted to extend their understanding of ПЂ, sometimes by computing its value to a high degree of accuracy. The transcendence of ПЂ implies that it is impossible to solve the ancient challenge of squaring the circle with a compass and straightedge.

It is a transcendental number, meaning that it cannot be a solution of an equation involving only sums, products, powers, and integers. Consequently, its decimal representation never ends, nor enters a permanently repeating pattern. It is an irrational number, meaning that it cannot be expressed exactly as a ratio of two integers, although fractions such as 22/7 are commonly used to approximate it. The number ПЂ appears in many formulas across mathematics and physics. The number ПЂ ( / p aЙЄ/ spelled out as ' pi') is a mathematical constant that is the ratio of a circle's circumference to its diameter, approximately equal to 3.14159.

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