About numerals, dust boards, scrolls and fingermath
by Duncan Boutwell
Jan 15, 2013 | 2311 views | 0 0 comments | 15 15 recommendations | email to a friend | print
By the phone on a yellow sticky note was a phone number in my own handwriting. The shape of my numbers brought back when my third grade teacher and I got crosswise over the “correct” way to write Arabic numerals. Recently, I Googled “Arabic numerals” to see if I could find some that didn’t remind me of third grade. I found surprises, not only about how Arabic numerals became our own but also some of the unique ways these numerals were employed. Two points were worth writing about. The first is the use of dust boards. Think of them as primordial chalk boards. Any flat surface would work. The dust came directly from the street, and a finger served to make the marks. This system worked particularly well when the problem required changing the position of the numerals during the solution of the problem. It was not for the marketplace; most businessmen did the majority of their calculations with one of several forms of math that used only fingers, dactylonomy as it is called today. The dust board was more for use in schools. “Official scribes … ,” it was written, “avoid (dust boards) because it requires equipment. … They consider that a system that requires nothing but the members of the body (fingers), is more fitting to the dignity of a leader.” Scribes had other problems regarding numerals. Try this for yourselves. Write the numerals one to nine and a zero, in the way that scribes had to write anything. Sitting cross-legged on the ground with a scroll partially unrolled and balanced on their legs, they would write a single line vertically, starting from the bottom. The next line required a careful unwinding from a blank section on the left and a winding of what they had written onto a filled-in part of the scroll on the right. Here’s the catch: Maybe the scroll was written that way, but it wasn’t read that way. It was read holding the scroll horizontally and reading it right to left. Everything the scribes wrote had to be offset 90 degrees. Sometimes they forgot. In fact, they forgot so frequently that in less than a century, the numerals for both two and three became permanently rotated. The numerals we use today are actually turned 90 degrees from the original. I wish there were more space for dactylonomy; calculating with fingers is considered important for the development of the brain. Somehow, part of the brain’s abilities can be outsourced to the hands. Players of musical instruments like a piano, that develop muscle memory in both hands are the beneficiaries of enhanced intelligence in areas that require time and space coordination. “The Complete Book of Fingermath,” by Edwin M. Lieberthal, describes his subject as “a simple technique for turning your ten fingers into a calculator. A calculator that’s not only simple, scientific, accurate and speedy but accessible to everyone.” I hope he’s right. Otherwise, I blew 25 cents at a local book sale.
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