The African Calculator" was Thomas Fuller (1710-1790), a Virginia slave who could neither read nor write, but who could quickly solve complex math problems in his head. He was once asked how many seconds a man had lived if he was 70 years, 17 days, and 12 hours old. It took Fuller only a minute and a half of mental arithmetic to answer: 2,210,500,800 seconds. One of his questioners laboriously worked out the calculation with pencil and paper, told Fuller he was wrong, and triumphantly gave another answer. In response, Fuller simply said, "You forgot the leap years." Little is known of Fuller's life. He was stolen from his family in Africa at the age of 14, and sold into slavery. His owner was Mrs. Elizabeth Cox who lived in Alexandria, Virginia, and Fuller spent his life as a laborer on her plantation. His reputation as a mathematical genius spread, however, and visitors came to ask him difficult arithmetic questions, which he was always able to answer quickly and correctly. On behalf of the Abolition Society of Pennsylvania, Benjamin Rush, the Philadelphia physician, sent Thomas Fuller's name to London in answer to a request for information on blacks of unusual intellectual ability. The scientific belief of the day was that Africans were mentally inferior to Europeans, and anti-slavery organizations were always seeking evidence to refute the claim. So even as an illiterate slave, Thomas Fuller was able to help in the struggle for freedom---because he could solve math problems in his head.