An Exhibition themed on Japanese Traditional Mathematics

An exhibition which introduces Japanese traditional mathematics is being held from April 28th to June 17th, in Sano city. The display consists of 70 pieces of valuable historical materials. A "sangaku", wooden mathematical puzzle tablet to dedicate to Shinto shrines or temples, is included among them, and it is considered as the oldest sangaku in Japan.

Mathematics was introduced from China, during the Nara period, and after the Edo period that was evolved as Japanese unique mathematics according to the development of civil construction, industry, and commerce. At that time, a mathematical textbook "Jingo-ki" by Mitsuyoshi Yoshida was published and became a bestseller. The book was widely spread among the general public so that not only upper class but common people could also enjoy solving mathematical puzzles.

There was a custom to dedicate a sangaku, when somebody has succeeded to solve a very difficult puzzle, as a token of his gratitude to the gods and in hope that he would devote more efforts to his studies. Because there were many visitors to shrines and temples, to dedicate sangakus had been good opportunity to perform and publish achievements by mathematicians. In the most cases, both of mathematical puzzles and its answers were written on sangaku. But in some cases, the puzzle which is most difficult to solve was written without its answer for purpose of present a challenge to the visitors. It was alternated with other sangaku only after somebody could succeed to solve that puzzle.

https://www.sankei.com/region/news/180518/rgn1805180039-n1.html