Ramanujan, the son of a clerk, was born into a poor Brahmin family in Erode near Madras, India. Sometime in 1903, while a student at Kumbakonam High School, he acquired a copy of G. S. Carr's Synopsis of Elementary Results in Pure Mathematics. Carr is an unusual work, normally of use as a reference work for a professional mathematician: it consists of about 6000 theorems presented without comment, explanation, or proof. Ramanujan set himself the task of demonstrating all the formulas, a task only a natural-born mathematician would contemplate, let alone pursue. Indifferent to other subjects, Ramanujan failed every exam he entered. For a time he was supported by Ramachandra Rao, a senior civil servant and secretary of the Indian Mathematical Society (IMS). In 1912 he took a clerical position with the Madras Port Trust. At the same time it was suggested that he should seek the advice of a number of British mathematicians about his work and career.

In January 1913 Ramanujan sent a letter to a number of British mathematicians containing a number of formulas. This led to an important correspondence with the Cambridge mathematician G. H. Hardy. Hardy noted that, while some of the formulas were familiar, others “seemed scarcely possible to believe.” Some he thought he could, with difficulty, prove himself; others, he had never seen anything like before, and they defeated Hardy completely. Despite this, it was obvious to Hardy that the formulas must be true and could only come from a mathematician of the very highest class. With Hardy's backing, Ramanujan was awarded a scholarship by the University of Madras and invited to visit Cambridge.

There were, however, religious problems facing the devout Ramanujan but these were resolved when the goddess Namagiri appeared in a dream to Ramanujan's mother absolving him from his traditional obligations. By June 1913 Ramanujan was in Cambridge working with Hardy. They collaborated on five important papers. Ramanujan was elected to the Royal Society in 1918, the second Indian to be honored in this way (the engineer Ardaseer Cursetjee Wadia was elected in 1841), and was made a fellow of Trinity College, Cambridge, in 1919. By this time his health had begun to fail. He returned to India in 1919 and died soon after from TB.

Part of Ramanujan's mathematical ability came from his ability to do mental calculations extremely quickly. It is said that he was once visited by Hardy, who remarked that the number of the cab he had ridden in, 1729, was a dull number. “No,” replied Ramanujan, “it is a very interesting number; it is the smallest number expressible as a sum of two cubes in two different ways.” (1729 = 1³+12³ and 9³+10³.)