# Srinivasa Ramanujan

Srinivasa Ramanujan was born on 22nd December, 1887 in Erode district of Tamil Nadu. He was considered as doyen of number theory, infinite series, mathematical analysis, and making formulas and equations without any formal training in pure mathematics.

During his five-year stay in Cambridge, he published 21 papers, five of which were in collaboration with Prof. G.H. Hardy. His achievements at Cambridge include the Hardy-Ramanujan circle method in number theory and Roger-Ramanujan’s identities in partition of integers. He worked on composite numbers, algebra of inequalities, probability theory, continued fractions etc.

Once when Hardy visited him in the hospital, he mentioned as a way of greeting that the number of the taxi he had come in was 1729. He added that he thought it was “rather a dull number.” From his sick bed, Ramanujan protested. “No, Hardy”, he said, “it is a very interesting number. It is the smallest number that can be expressed in two different ways as the sum of two cubes.” As usual he was right because 1729 can be written as 103+93 and also as 123+13.

Ramanujan’s “deathbed” puzzle is a cryptic formula that he believed came to him in dreams while on his deathbed. In his deathbed in 1920 he had written, in a letter to his mentor G.H. Hardy, about the formula outlining several new mathematical functions together with a theory about how they worked. Recently (2012) the American researchers claim that they have solved the “deathbed” puzzle after more than 90 years. The new findings, which prove the formula right, could explain the behaviour of black holes.

#### Contribution in Mathematics

• As a mathematical genius, he had compiled more than 3900 mathematical results and equations.
• His Ramanujan Prime and Ramanujan theta discoveries had inspired further research on this mathematical subject.
• Along with British Mathematician Hardy, Ramanujan had discovered the smallest number represented as sum of two cubes 1729 which is known as Hardy-Ramanujan number.

#### National Mathematics Day, India

In 2011, Indian Government had declared 22nd December as ‘National Mathematics Day’ to celebrate  125th birth anniversary of S Ramanujan.

#### National Mathematics Year, India

Indian Government also had declared, 2012 as National Mathematics Year in the memory of S Ramanujan.

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