Writer and enigmatologist Paul Hoffman speaks about the time he spent with one of the world's most gifted mathematicians. Gelf Magazine presents Geeking Out, a free, monthly speaking series featuring some of the best science writers and researchers around. Visit www.gelfmagazine.com, where you can read interviews with April's featured speakers: Glen Whitney, founder of the Math Factory; noted enigmatologist and author Paul Hoffman; and John Derbyshire, author of popular mathematically-themed books.