The Man of Numbers by Keith Devlin

Man of NumbersInformation

Goodreads: The Man of Numbers: Fibonacci’s Arithmetic Revolution
Source: Library
Published: 2011


Devlin examines the impact of the arithmetic book of Leonardo of Pisa, commonly known as Fibonacci.


I picked up this book with the mistaken impression that it told the life of Fibonacci and, consequently, found myself disappointed.  As Devlin explains, history knows very little about Fibonacci; generally, we know only that his real name was Leonardo of Pisa, that he travelled to Africa while a teen (and learned there the Hindu-Arabic number system), that he wrote quite a few books on mathematics (one of which inspired Europe to adopt the Hindu-Arabic number system), and that he was considered important as a result.  Add a few more random details like visits to emperors and what his father did for a living, and you have just about everything.  So, of course, I found myself wondering how the author managed to get 158 pages out of it.

Had I read the subtitle more carefully, I might have suspected that the book does not focus on the life of Fibonacci, but on the results of his publications, particularly his Liber abbaci, which taught how to use the Hindu-Arabic number system in everyday situations.  That means that Devlin devotes chapters to topics like the sources Fibonacci used to write his book or the books that his book inspired.  Other full chapters illustrate in detail the methods Fibonacci used to calculate (notation was different then and explanations of problems we would find simple needed pages of explanations).  Not being a historian of mathematics, I found myself rather bored by the lists of book titles, the intricacies of which author wrote which manuscript, and, above all, the multitude of lengthy quotations from Liber abbaci.  After the first two or three, I felt like I’d gotten it—it took Fibonacci an insufferably long time to explain stuff.

If you are the type of person interested in the question of whose mathematic manuscript inspired whose, this book will no doubt appeal to you.  (If, on the other hand, this concept seems strange to you, consider that students of literature often try to decipher what works inspired various authors—the question really does matter to some people.)  I, however, found myself longing for other information—if not biographical details, then maybe some more information on everyday life in medieval Pisa or an explanation of what other mathematic and scientific advances were occurring around that time.  Expecting to discover Fibonacci, I was disappointed to discover his absence.

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2 thoughts on “The Man of Numbers by Keith Devlin

    • Krysta says:

      I was expecting this to be about the life of Fibbonacci, so even though I like reading about math, I was kind of disappointed to find myself reading pages about how to solve algebraic problems the old-school way. So anyone familiar with basic algebra can probably follow along. The question is whether you want to and, well, I kind of wonder how many people do. One or two examples of problems would have been sufficient, as far as I’m concerned!


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