June 22, 2008 12:41:31
Posted By Peter Bentley
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Here's a recent email exchange about the history of numbers, relating to the descriptions in
The Book of
Numbers
One month ago I finished reading your fascinating book "the Book of Numbers". From that moment on your question: Where are all the girls? keeps lingering through my mind. I wonder how many girls did react on this question. I'm glad you enjoyed the book. So far you are the first to tell me about your reaction to that specific question. Let's hope a few more girls do become more interested in the subject!
You wrote about Euler, Pierre de Fermat and Descartes concerning amicable numbers.
I just happened to read the following text on the internet: Arabic mathematics : forgotten
brilliance?
http://www-groups.dcs.st-and.ac.uk/~history/HistTopics/Arabic_mathematics.html
…Continuing the story of amicable numbers, from which we have taken a diversion, it is
worth
noting that they play al large role in Arabic mathematics.
Al-Farisi (born 1260) gave a new proof of Thabit ibn Qurra’s theorem, introducing important
new
ideas concerning factorisation and combinatorial methods. He also gave the pair of amicable
numbers 17296, 18416 which have been attributed to Euler, but we know that these were
known
earlier than al-Farisi, perhaps even by Thabit ibn Qurra himself. Although outside our time
range
for Arabic mathematics in this article, it is worth noting that in the 17th century the Arabic
mathematician Mohammed Baqir Yazdi gave the pair of amicable number 9,363,584 and
9,437,056 still many years before Euler’s contribution……
Perhaps it is of interest for you.
yes, when describing amicable numbers I wrote "(although some claim that they
may also
have been known before this)". I was referring to this text you found. There is some debate
over
the issue, but it is probably true that the Arabs had found many amicable numbers, which
were
then forgotten for several hundred years and rediscovered by the likes of Descartes and
Euler.
The University of St Andrews is an excellent source of information on this topic - I used their
help
when writing the Book of Numbers.
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