| Although it is not known when the abacus, used for everyday calculations until the time the electronic calculator became widely used, was introduced to Japan, there is an explanation of the method of calculating using an abacus in "Warizan sho" (the Book of Division) written by Shigeyoshi MORI in 1622. |
日常の計算を電卓の普及まで担い続けたそろばんは、いつ導入されたかは不明であるが、毛利重能の『割算書』（1622年、元和８年）ではそろばんを用いた計算が解説されている。 |