In 2001, Stanford mathematician Dr Keith Devlin, also known as ‘The Math Guy’ on NPR’s Weekend Edition, set out to research the life and legacy of the thirteenth century mathematician Leonardo of Pisa, popularly known as Fibonacci. Leonardo introduced the Hindu-Arabic numeral system and arithmetic to the Western world, and thereby helped start a global, social and economic revolution. Devlin recounted Leonardo's story in a 2011 book titled The Man of Numbers: Fibonacci’s Arithmetic Revolution. In a simultaneously published companion e-book, Leonardo and Steve: The Young Genius Who Beat Apple to Market by 800 Years, he drew remarkable parallels between the careers of Leonardo and Apple’s Steve Jobs. His new book, Finding Fibonacci: The Quest to Rediscover the Forgotten Mathematical Genius Who Changed the World is a first-hand account of his experiences in uncovering the story, reconstructed from his project diary and notes, together with stories of three other contemporary scholars who were also motivated to find out about the long-forgotten medieval mathematician who did so much create the world we live in. This talk was held as part of the Sydney Ideas program on 3 October: http://sydney.edu.au/sydney_ideas/lectures/2017/keith_devlin.shtml