The boy who loved math : the improbably life of Paul Erdos
Heiligman, Deborah.
Paper Book
Most people think of mathematicians as solitary, working away in isolation. And, it's true, many of them do. But Paul Erdos never followed the usual path. At the age of four, he could ask you when you were born and then calculate the number of seconds you had been alive in his head. But he didn't...