The Man of Numbers: Fibonacci's Arithmetic Revolution is Devlin's latest book.
"The Man of Numbers," at 156 pages (plus notes, bibliography, and index) and ten chapters is a fairly quick read. Leonardo of Pisa, also known as Fibonacci, is mostly only known for the Fibonacci sequence. Devlin shows us that there was much more to Fibonacci's life and that, in fact, Fibonacci played a very key role in the marketing of arithmetic in 1202 to the world of commerce in Western Europe through his book, Liber Abacci (The book of calculation.)
I'm not going to review the book chapter by chapter as you can find that kind of information on the web. NPR has a nice review, an excerpt from the book, and an audio interview with Mr. Devlin. ScienceNews.org has a review and Amazon.com has several reviews. But, I will point out some items of particular interest.
Not much is known about Fibonacci's life nor about the sources Fibonacci consulted for his legacy so it's easy to appreciate what Devlin was able to learn about this man and his great work. For those of you who want a taste of what is in the Liber Abacci, Chapter Five presents an overview. Fortunately for us, we don't need to read the Liber Abacci in its native scholarly Latin as Devlin has used his talent for making math accessible to mathematicians and non-mathematicians alike. Liber Abbaci had fifteen chapters which included arithmetic, algebra, fractions, some geometry, working with money, word problems, and extracting square and cube roots. (This blog article and Wikipedia page dive into the Liber Abbaci and, in 2003, Springer published an English translation by Laurence Sigler.
Why was Fibonacci's work important? Two big reasons. First, Fibonacci helped business people to learn the arithmetic they needed for commerce. I highly recommend this article, from Keith Devlin's blog, about another work of Fibonacci, his lost "book for merchants." The second reason that Fibonacci was such an important figure was that he saw the value of his work and was able to commercialize it. In another blog post, Devlin likens the marketing of his work to the first personal computer revolution.
The people who showed him the invention were fascinated by how it worked, but they clearly did not see what the young man could: its huge commercial potential. As so often happens in history, the right person was in the right place at the right time. Not only had the young man shown mathematical talent at an early age, he had grown up in what was then the acknowledged world capital for innovation, particularly in the business world. He also had the savvy to know how to make the invention available to ordinary citizens. The trick was to package and market it to them directly, in a way that they could at once appreciate and understand.
"The Man of Numbers" is a good read, especially for those of us interested in the history of mathematics and its key figures. It's not at all a difficult read and it broadens our horizons beyond the confines of a sequence of integers.