[つるかめざん, tsurukamezan] (n) obtaining the respective numbers of cranes and tortoises from the total of their heads and legs; calculating the values of two unknown quantities from their unit total and the total of one of their attributes
[べっこう, bekkou] (n) (1) (See 玳瑁) tortoiseshell (of the hawksbill turtle); bekko; (2) (See 鼈) (in Chinese medicine) tortoiseshell (esp. of the Chinese soft-shelled turtle)