<P> The Hellenistic period began in the 4th century BC with Alexander the Great's conquest of the eastern Mediterranean, Egypt, Mesopotamia, the Iranian plateau, Central Asia, and parts of India, leading to the spread of the Greek language and culture across these areas . Greek became the language of scholarship throughout the Hellenistic world, and Greek mathematics merged with Egyptian and Babylonian mathematics to give rise to a Hellenistic mathematics . Greek mathematics and astronomy reached a rather advanced stage during the Hellenistic and Roman period, represented by scholars such as Hipparchus, Apollonius and Ptolemy, to the point of constructing simple analogue computers such as the Antikythera mechanism . </P> <P> The most important centre of learning during this period was Alexandria in Egypt, which attracted scholars from across the Hellenistic world, mostly Greek and Egyptian, but also Jewish, Persian, Phoenician and even Indian scholars . </P> <P> Most of the mathematical texts written in Greek have been found in Greece, Egypt, Asia Minor, Mesopotamia, and Sicily . </P> <P> Archimedes was able to use infinitesimals in a way that is similar to modern integral calculus . Using a technique dependent on a form of proof by contradiction he could give answers to problems to an arbitrary degree of accuracy, while specifying the limits within which the answer lay . This technique is known as the method of exhaustion, and he employed it to approximate the value of π (Pi). In The Quadrature of the Parabola, Archimedes proved that the area enclosed by a parabola and a straight line is 4 / 3 times the area of a triangle with equal base and height . He expressed the solution to the problem as an infinite geometric series, whose sum was 4 / 3 . In The Sand Reckoner, Archimedes set out to calculate the number of grains of sand that the universe could contain . In doing so, he challenged the notion that the number of grains of sand was too large to be counted, devising his own counting scheme based on the myriad, which denoted 10,000 . </P>

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