WHEN HIS FRIENDS played in the street, the boy on the porch sometimes looked up to watch, calling out to them, and smiling at their games. More often, though, he did not even notice them. For Srinivasa Ramanujan, the beautiful and compelling calculations on his slate were all the entertainment he needed.
Ramanujan was born in 1887, in south India, and grew up in Kumbakonam, about 160 miles south of the port city of Madras. His parents were poor: his father was a store clerk, and his mother sang in the temple. The family boarded college students to bring in extra money.
A quiet, sensitive, and pleasant boy, Ramanujan showed his talent for mathematics from the moment he started his studies. By the time he was eleven, school mathematics was…