Nick,

      This is a very good "mathematical biography" of 
    Leonardo Pisano ("Fibonacci"), focusing not only on the practical
    applications of the Hindu-Arabic numerals that he helped
    to popularize, but on the many other contributions he made  
    besides that. One thing you didn't mention, but that 
    is decidedly odd, is that he is mostly known today by a 
    name that he would not have recognized (he never used it 
    himself), and that he is best remembered for what amounts
    only to a very small part of what he did. This is not all
    that rare, though.  What is remembered of a mathematician's
    work is mostly determined by what other people are able to
    understand and make use of.  

      One comment about what you say about the adoption of
    the Hindu-Arabic numerals:  Although people could get
    very fast and adept with arithmetic on an abacus, a real defect
    for business was that once the calculation was finished,
    there was no record apart from the final answer.  That
    meant there was really no way to check a result except
    to repeat the whole calculation!  With arithmetic done
    with written numerals on paper, you do have a complete 
    record and you can check the results by verifying the steps!
    I think this was also a factor in the success of the
    Hindu-Arabic numerals after they were explained by 
    an advocate such as Fibonacci.  
  
      The main comment I have is that I am really glad that
    looked for more information about his book called the 
    "Liber Quadratorum" (Book of Squares)
    in addition to other the works that you discuss.  There, we
    can see some direct influence from the Diophantos-style
    theory of solving numerical equations.  This work also
    became the source of later results in number theory by
    some very influential 18th and 19th century mathematicians.


    Grade:  A