# Population in India

HISTORY AND EVOLUTION OF PI (π)

Archimedes found pi to be 22/7 in the year 240 B.C.3 Importance of Pi which enters into all branches of mathematics like Theoretical – Physics – Chemistry – Astronomy etc. The universe could not operate properly without the number pi. The Pi day is celebrated on the same day of Albert Einstein’s birthday. The symbol π comes from a Greek letter for the ratio of a circle’s circumference to its diameter .Albert Einstein used pi for his formula of general relativity. Pi is used in Geometry and Trigonometry .Pi is used to find the area and circumference of a circle .It is also used to find the area and volume on spheres Pi is often defined using trigonometric functions

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".

The ubiquity of π makes it one of the most widely known mathematical constants both inside and outside the scientific community: Several books devoted to it have been published, the number is celebrated on Pi Day and record-setting calculations of the digits of π often result in news headlines.

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Leonhard Euler

Leonhard Euler popularized the use of the Greek letter π in works he published in 1736 and 1748. The earliest known use of the Greek letter π to represent the ratio of a circle's circumference to its diameter was by Welsh mathematician William Jones. William Oughtred used π and δ, the Greek letter equivalents of p and d, to express ratios of periphery and diameter in the 1647.

Srinivasa Ramanujan, working in isolation in India, produced many innovative series for computing π.   [pic]

The development of computers in the mid-20th century again revolutionized the hunt for digits of π. John von Neumann was part of the...