The Plum-Blossom Wedge Product Method for Multiplication and Division of Multi-digit Integers

For two integers $a$ and $b$, the plum-blossom product of $a$ and $b$ is defined as the ones of the usual product of $a$ and $b$ if the ones is less than or equal to $3$, or otherwise as the ones minus $10$. Under this operation, all integers is a commutative semigroup. Since some fine properties of this semigroup, the plum-blossom product method is the efficient method of multiplication and division of long integers, can be used to mental arithmetic and to computer science. In this paper, we improve the theory of plum-blossom products so that the new concept–the plum-blossom wedge product is proposed. The plum-blossom wedge product is also of some good features so that it can be applied to multiplication and division of long integers. The plum-blossom wedge product method of multiplication and division is not only efficient in mental arithmetic, but also could applied to improve the design of multipliers and dividers of computer.