> > > koala"although technically, isn't it still counting on your fingers?"mom
> >
> > Perhaps, but I can store larger numbers this way.
>
> I'd like to be able to count in binary on my hands. If you consider each finger a binary digit, which is up for a '1' and down for a '0', you can store the numbers 0-31 on each hand. If you use both hands together, to store a single number, the range of values is 0-1023.
>

I admire that both you and Dave have not only thought about counting in binary on your hands, you've actually tried it. Of course the inherent difficulty is that we're not intuitively trained to think in binary; so this is quite a hurdle, as you've noted. (Pardon me if I tend to disbelieve wintermute's implication that his agile fingers are used to frequently "store" numbers from 0-1,024.) That seems like an unlikely degree of effort to invest just for counting things, if one isn't able to add, multiply, and subtract in binary, too.


> I started trying to do this during family cook-outs, when it was my job to find out how many hamburgers and hot dogs everybody wanted. I have a large family, and when each one of them is saying things like "one hamburger, two hot dogs" then one must use pencil and paper...unless one is HARDCORE or a geek or something. I'd try to use one hand to count hamburgers, one hand to count hot dogs, and store the numbers in binary.
>
> Generally I'd screw up the binary math somehow and get the numbers wrong, but in theory, practice should make one able to count in binary on one's fingers efficiently, without thinking about it. I'd love to be able to do that, but I'm not so sure I want that skill enough to practice it.
>
> S "besides, representing the number '4' is rude" am
>

Actually, years ago I first heard there *is* an effective and fairly ancient form of rapid-fire fingermath, used by Korean merchants. It's called Chisanbop, and its utility arises from using the hands as a form of natural Abacus based on units of 1, 5 and 10. The advantage is that you can add, subtract, multiply, and divide on your fingers with very little thought and you simply "feel" up the final tally at the end. I think the main disadvantage is that you're limited to manipulating strings of small double-digit figures only.

An Explanation of Chisanbop:
http://forum.swarthmore.edu/dr.math/problems/harbin3.18.96.html
(If you follow the
http://klingon.cs.iupui.edu/~aharris/chis/chis.html
link, you'll need RealPlayer installed to see the streaming lessons in Chisanbop +/-/x/÷ )

Andy Harris' original page gives many examples of the more problematic problems in fingermath:
http://klingon.cs.iupui.edu/~aharris/basicComputing/bc5a.html

If anyone can find any other pages on this subject, I'd appreciate it. :-)