We need help with: On the flight from California to Philadelphia I was reading a book, "Pi in the Sky, Counting, Thinking and Being" by John D. Barrow and from that I thought it would be interesting to find out all the different ways different people around the world use their hands to show counting.
I wrote my "keypal" Musumi Suzuki today the following message:
******* Dear Mutsumi,
Could you tell me how you count on your fingers in Japan? I am reading a book called "Pi in the Sky" and the author talks about different cultures using their hands to count. Some people show the numbers 1 to 10 on their fingers by starting with the palm open and others are the opposite - they start with the palm closed. I started thinking that when I was in Germany they show "2" by extending the thumb and the index finger while American's typically extend the index finger and the middle finger to show "2".
So I am asking various "keypals" how they show numbers with their fingers. I just find it interesting. I am also curious whether the palm of the hand is facing or the back of the hand is facing you as they show the fingers representing the numbers.
We Japanese start with open palm facing, and follows as;
one---> fold thumb two----> thumb and index finger three--> thumb, index finger and middle ... five---> closed palm six----> open little finger seven--> little and ring finger ... ten----> open palm.
To show two, we use extended index and middle fingers, with back of hand facing me (palm side facing towards the person to show the number).
To show five we use open palm (not closed, differs from the above counting system).
Really interesting problem! Mutsumi
My "help" question is that I would love help gathering more data on this question. The reason I find this of interest is that I have always thought it worthwhile to demonstrate to students that "math" was not written (or invented!) by one person. I like to get students engaged in thinking of the development of mathematics and why it has developed. I think the idea of counting is such a basic concept and could be fun to use to open a discussion on the development of mathematics.
If I receive a variety of answers as I am expecting,it would make a fun Web page and possibly an activity.