出典:Wikipedia
出典:『Wikipedia』 (2011/06/29 10:29 UTC 版)
Counting rods (simplified Chinese: 筹; traditional Chinese: 籌; pinyin: chóu; Japanese: 算木, sangi) are small bars, typically 3–14 cm long, used by mathematicians for calculation in China, Japan, Korea, and Vietnam. They are placed either horizontally or vertically to represent any number and any fraction.