Hand calculator with paper counting rods, Kangxi period (1662—1722). Brass, paper rolls and iron in wooden case, paper and iron. 5×19 x 11.5 cm. The Palace Museum, Beijing.
Hand calculator with paper counting rods, Kangxi period (1662—1722). Brass, paper rolls and iron in wooden case, paper and iron. 5×19 x 11.5 cm. The Palace Museum, Beijing.
