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Chinese Foundation of Japanese Math
Plate 2.4. Ruthless thieves stealing a roll of cloth appeared in the Jinko¯ - ki of 1643, but the problem was taken from the Sun-Tsu Suanjing. We present it here as problem 2-2.
This problem appeared in the original Jinko¯ -ki of 1627 as well. The solution is on page 54.
Problem 2-4 In a cage, there are some roosters and hares. The total number of necks is 35 and the total number of feet is 94. How many roosters and hares are in the cage? The roosters and hares appeared in the Inki Sanka of 1640 (chapter 3) and as cranes and turtles in the 1815 Japanese book Sanpo¯ Tenzan Shinanroku by Sakabe Ko¯ han (1759–1824). The solution is on page 54.
Problem 2-5 On the top of a gate, one can see nine banks; on each bank there are nine trees, each of which has nine branches. On each branch, there are nine nests, in each nest live nine adult crows, each of which has nine chicks. Each chick has nine feathers and each feather has nine colors. How many trees, branches, nests, crows, chicks, and colors are there? Answer on page 54.