Srīnivāsa Rāmānujan was an Indian mathematician and autodidact who, with almost no formal training in pure mathematics, made extraordinary contributions to mathematical analysis, number theory, infinite series and continued fractions. Ramanujan was said by the English mathematician G.H. Hardy to be in the same league as mathematicians like Euler and Gauss in terms of natural genius. He was born on 22na of December 1887 in a small village of Tanjore district, Madras. He failed in English in Intermediate, so his formal studies were stopped but his self-study of mathematics continued.

.[9] His father, K. Srinivasa Iyengar, worked as a clerk in a sari shop and hailed from the district of Thanjavur.[10] His mother, Komalatammal, was a housewife and also sang at a local temple.[11] They lived in Sarangapani Street in a traditional home in the town of Kumbakonam.
Born in Erode, Madras Presidency, to a poor Brahmin family, Ramanujan first encountered formal mathematics at age 10. He demonstrated a natural ability, and was given books on advanced trigonometry written by S. L. Loney.[2] He mastered them by age 12, and even discovered theorems of his own, including independently re-discovering Euler's identity.By 17, Ramanujan conducted his own mathematical research on Bernoulli numbers and the Euler–Mascheroni constant. He received a scholarship to study at Government College in Kumbakonam, but lost it when he failed his non-mathematical coursework. He joined another college to pursue independent mathematical research, working as a clerk in the Accountant-General's office at the Madras Port Trust Office to support himself.
In mathematics, there is a distinction between having an insight and having a proof. Ramanujan's talent suggested a plethora of formulae that could then be investigated in depth later. It is said that Ramanujan's discoveries are unusually rich and that there is often more to them than initially meets the eye. As a by-product, new directions of research were opened up. Examples of the most interesting of these formulae include the intriguing infinite series for π,
One of the intriguing infinite series for pi by s.ramanujan
He sent a set of 120 theorems to Professor Hardy of Cambridge. As a result he invited Ramanujan to England. Ramanujan showed that any big number can be written as sum of not more than four prime numbers. He showed that how to divide the number into two or more squares or cubes.

The Ramanujan conjecture: Although there are numerous statements that could bear the name Ramanujan conjecture, there is one statement that was very influential on later work. In particular, the connection of this conjecture with conjectures of André Weil in algebraic geometry opened up new areas of research. That Ramanujan conjecture is an assertion on the size of the tau function, which has as generating function the discriminant modular form Δ(q), a typical cusp form in the theory of modular forms. It was finally proven in 1973, as a consequence of Pierre Deligne's proof of the Weil conjectures. The reduction step involved is complicated. Deligne won a Fields Medal in 1978 for his work on Weil conjectures.[88] Ramanujan–Hardy number 1729: when Mr Litlewood came to see Ramanujan in taxi number 1729, Ramanujan said that 1729 is the smallest number which can be written in the form of sum of cubes of two numbers in two ways, i.e. 1729 = 93 + 103 = 13 + 123 since then the number 1729 is called Ramanujan’s number. In the third century B.C, Archimedes noted that the ratio of circumference of a circle to its diameter is constant. The ratio is now called ‘pi ( Π )’ (the 16th letter in the Greek alphabet series) The largest numbers the Greeks and the Romans used were 106 whereas Hindus used numbers as big as 1053 with specific names as early as 5000 B.C. during the Vedic period

S. Ramanujan wrote down all his mathematical findings, in ledger-like notebooks that lately became famous as "Ramanujan`s Frayed Notebooks". All those findings were actually a treasure trove of creative mathematics and the Notebooks contain about 4,000 theorems, formulas, corollaries and examples. According to G. H. Hardy, at least two-third of the mathematics in the notebooks was totally novel, and none of the western mathematicians touched them before. Ramanujan was also considered as the master of numbers. His most outstanding contribution was his formula for p (n), the number of `partitions` of `n`. For all these reasons, Ramanujan is hailed as an all time great mathematician .