To: Teacher2Teacher Public Discussion
This was popular back in the 1970s. I used to teach this technique to my students and to other teachers. It was interesting, and some kids loved it. I still use it when I am adding a long column of numbers and don't have a calculator handy, but mostly just for fun. Remember - back then we didn't have access to all the calculators we have today. Here is a link to a good explanation. http://www.cs.iupui.edu/~aharris/chis/chis.html There are books available online, but only used, and quite expensive. Our public library actually has a copy, so you might try your library.
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