September 26, 2008

Mathematics festival of Tottori prefecture and “Jinkoki”

Tottori prefecture co-hosts with Tottori University the annual event called “Science World”. Under this year’s theme “Beautiful mathematics and enjoyable arithmetic”, the study group of Tottori University led by Prof. Toshiaki Yabe has created the enjoyable world. I don’t know why but I was invited to give a lecture there. It was such an enjoyable event that the venue was fully crowded with adults and children tackling with numbers, figures and quizzes.

There were a variety of corners arousing participants’ interests such as: “Let’s play with three thousand blocks” “Let’s make a kaleidoscope” “I see, this is the graph” “Catch Lupin” “World of curved surface” “Wonders of square measure” “Moebius strip” “Challenging mathematics” “Paper mine sweeper” “Wonders of calendar” “Cubic models” “Challenging one stroke writing” “Visible world of magnet” “Wonders of pentagram” “Magic square” “Tiling” “Let’s make an ornament” “Let’s play with making Seisho-nagon wisdom plate” “Challenging Pythagorean theorem” “Numbers guessing magic” “Komachi mathematic puzzle”. In addition, there were event corners of making paper-craft, testing calculating ability and trying to put on spacesuit. It was so well managed with quiz rally to have integrated all corners into one wonderful event. I really wanted to stay there for whole day through.

As I went round the venue, remembrance came to my mind of “Jinkoki” written by Mitsuyoshi Yoshida in Kan-ei ages of Edo period. This book seemed to have been written intended for as an instruction manual for the maximum use of abacus then prevailing. As to the abacus, it is described in the book titled “Fudoki of Japan; Landscape of Japan” written in China in 1570’s and introduced in there as already used in Japan in those times. And also, the abacus that Toshi-ie Maeda (a warlord of warlike age) used in the camp of battlefield is preserved. There is a record that says the abacus was already in use by common people in Muromachi period (1336~1573).

“Jinkoki” is very interesting indeed. Somewhat different from ordinary manuals, the book is illustrated with many pictures drawn by professionals to draw attention from readers and used friendly explanation with full sense of humor in example problems. For instance, in the problem of “add and subtract” so-called today, the book used an expression of “thief calculation” wherein the group of thieves is sharing alike the stolen silk under the bridge above where passer-by people are overhearing thieves’ dealing and guessed how many thieves would be down there and how many pieces of silk were stolen. It is worthy of the then best seller of its unique technique to arouse people’s laughing interest in mathematics that is usually hard to learn. Its big hit brought an impact to the world of Japanese mathematics in later times.

There is a noodle shop called “Ichiokuchou; million-trillion” near my office. It is generally understood there is no such unit like “million-trillion” but in the first edition of “Jinkoki” published in 1627, the numbers are divided by single digit like; one, ten, hundred, thousand, ten thousand and so on to 1048 (48th power of 10), beyond which is figured by four digits. However, in the edition of 1631 that introduced geometric progression, the numbers are grouped by four digits over ten thousand like it is used today, because they began to deal with enormous large numbers like repetition of doubling figures, i.e. ten-thousand ten-thousand became a hundred million. Then the name of noodle shop “million-trillion” would have been used to mean the unit of number somewhere from ten thousand to one million. The expression often used in past to accentuate the scale of nation as “people of million-trillion” might have been used in a real sense of term in those times.

Now back to the present time to “Science World” of Tottori prefecture. I often hear people say, “When I was a child, I wanted to become an astronomical scientist but I wasn’t really good at mathematics so I gave up science course.” One of major reasons of disliking science despite very much fond of nature may lie in mathematics. If so, mathematics teachers must be more essentially involved in the problem of “science dislike”. This is what I’ve been feeling from a long time ago in my observation at various places in the country that there seems to be a sensitive problem lying between science teacher’s organization and that of mathematics. As this kind of “sensitiveness” among adults may amplify itself in the world of children, there must be something done realistically from the viewpoint of children.

I felt a premonition that the new world would be possibly opened by taking in naïve desire of children toward arithmetic and mathematics into the middle of science education. I came home to Tokyo by learning valuable lessons that it is very important to bring mathematics to the forefront education in a practical course of space education; to seek the way of co-studying science and mathematics; to bring the world of play as seen in Tottori event of “beautiful mathematics and enjoyable arithmetic” into practical education. I certainly went there to give them my lecture but came home the same day by learning a lot more.

I welcome your opinions on this column to the following E-mail address.
matogawa@planetary.or.jp

(Translated by The Planetary Society of Japan)

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