: to check the results obtained in multiplication, division, addition, and subtraction of integral numbers by a series of divisions by the factor 9 and comparison of the remainders obtained, the operation in multiplication being as follows: (1) divide each factor by 9, (2) divide the products of the remainders obtained by 9, (3) divide the number being checked by 9, the result being prob. correct if the remainders in operations (2) and (3) are equal
Useful english dictionary. 2012.