How Bill Gates knew he was different

The Harvard dropout who became a billionaire in his 30s, Bill Gates revolutionized the computer industry and, later, the world of philanthropy. Now he has been looking back at his childhood, with the first of a three-part autobiography fittingly titled “Source Code.” He discusses his rebelliousness and competitiveness with correspondent Lee Cowan, and talks about how, growing up, he viewed nearly everything through the prism of mathematics.