History of Hindu Mathematics: A Source Book v1.c8.s10.17

v1.c8.s10.17

It must be noted here that a complete set of rules for checking by nines is first found in India. Methods for testing multiplication and division were probably known to the Hindus much earlier. But as these tests were not considered to be among the fundamental operations, they were not mentioned in the works on *pâṭî-gaṇita*.¹ Nârâyaṇa seems to be the first Hindu mathematician to give rules for testing operations by the casting out of any desired number.