Leo is totally fixated on numbers and counting everything, even the words in the story the teacher reads; Lea is the shy new girl who shares his desk, and spends all her time drawing--but one day, in the noise of the playground, an accident brings them and their obsessions together in the beginning of a friendship.

In 2000, Keith Devlin set out to research the life and legacy of the medieval mathematician Leonardo of Pisa, popularly known as Fibonacci, whose book Liber abbaci has quite literally affected the lives of everyone alive today. Although he is most famous for the Fibonacci numbers--which, it so happens, he didn't invent--Fibonacci's greatest contribution was as an expositor of mathematical ideas at a level ordinary people could understand. In 1202,...