Chrs Devrs Tumblg How many social networking sites do we need, anyway?

Counting Number Angles

Date: 10/13/2002 at 13:25:53 From: Terri R Subject: Counting Number Angles  I am trying to find the history of counting number angles. I was told  by my professor that the way the numbers were written gave you the  number in the number of angles in the written number, such as the  number 2 being written as what we know as a Z: there are two angles  in this number, meaning it is the number 2. Can you give me more  information on this type of math history?

---

Date: 10/13/2002 at 23:42:35 From: Doctor Peterson Subject: Re: Counting Number Angles  Hi, Terri.  In Cajori's _A History of Mathematical Notations_ (p. 65), there is a  chart showing "Fanciful hypotheses on the origin of the numeral  forms." One of these (II) suggests that the numerals originated as  various numbers of dots, which were connected with lines; another (V)  shows various numbers of angles as you describe: __  __       _   _   _   __   _ /|   /   /  \/  |_  |_  ' /  \/  |_|_ |  /_  _\  /\  ,_| |_| _|_  /\  ,_| |  Cajori says, "A French writer, P. Voizot, entertained the theory that  originally a numeral contained as many angles as it represents units,  as seen in Part V. He did not claim credit for this explanation, but  ascribed it to a writer in the Genova Catholico Militarite. But  Voizot did originate a theory of his own, based on the number of  strokes, as shown in Part VI." __   __    __    __    __    __ |    |    |  |  |  |__   |__   |__|  /\  /\ |    |  __|  |__|   __|  |__|  |__|  \/  \/ /\  /\ \/  \/ /  These are all entirely imaginary explanations of the origin of the  symbols. It is not math history. To read about how they really  originated, see the article at the MacTutor History of Mathematics  archive at St. Andrews University:  The Arabic numeral system http://www-history.mcs.st-and.ac.uk/HistTopics/Arabic_numerals.html   If you have any further questions, feel free to write back.  - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/