Fibonacci: The Man Behind The Math In 1202 Leonardo da Pisa (aka Fibonacci) taught Western Europe how to do arithmetic with Arabic numerals. In Man of Numbers: Fibonacci's Arithmetic Revolution, Keith Devlin describes how basic arithmetic changed commerce, banking, science and technology.

Fibonacci's 'Numbers': The Man Behind The Math

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The book revolutionized commerce, banking, science and technology, and established the basis of modern arithmetic, algebra and other disciplines. And we do mean disciplines.

SIMON: Keith, thanks so much for being with us.

KEITH DEVILIN: Thanks, Scott. Good to be here again.

SIMON: This book sold even more copies than the monk's book of diet and exercise, didn't it?


DEVILIN: He ended up writing a smaller, easier to read version of that book. And in many ways it was a combination of the big scholastic book and the smaller easier to read version had freely as is that really causes one was in fact the world's first revolution.

SIMON: You compare him to some major figures today.

DEVILIN: This is Steve Jobs, Bill Gates. It's the computer revolution that we lived through in the 1980s and the parallels are actually uncanny.

SIMON: Well, take them up for us. 'Cause as I understand it, you know, zero to nine numerals had been around in Hindu and Arabic cultures for centuries.

DEVILIN: If you look at the beginnings of accounting, doubly entry bookkeeping, insurance, banking, all of that commercial stuff, it all came out of Pisa in the 13th century. And the key for that to happen was that people could do arithmetic efficiently for the first time in history.

SIMON: So why is Leonardo da Pisa referred to as Fibonacci?

DEVILIN: He was given that name by a historian. The name is actually comes from the Latin phrase: filius Bonacci. In the beginning of Leonardo's book, he says this is the book of calculation written by the son of Bonacci, filius Bonacci. He uses that phrase in the first opening sentence. And so, this historian in the 19th century takes up for his filius Bonacci, simplifies it to Bonacci. And for reasons, best known to himself, gives Leonardo that nickname.

SIMON: If "Libre Abaci" hadn't been written, would trading anything more than a couple of sacks of grain be possible?

DEVILIN: It would have happened, sure. I mean one of the things about almost all of mathematics is that it'll eventually surface and get used. It's a matter of who does it and when. And this is another of those similarities between Leonardo and Bill Gates and Steve Jobs and the people in the 1980s. And what Jobs did was simply take something that other people had developed and present it in a very easy to use way; and essentially turned computing into a consumer product. That's what Leonardo did.

SIMON: Thanks Keith.

DEVILIN: Oh, my pleasure, Scott. As usual.

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