Multiplication and distribution law, two numbers are multiplied by the same number, and their products add up, which is equal to the addition of two different numbers multiplied by the same number.

Law of addition and association: when adding three numbers, add the first two numbers and then the third number, or the last two numbers and then the first number, and the sum remains unchanged.

Multiplication and association law: when three numbers are multiplied, the first two numbers are multiplied by the third number, or the last two numbers are multiplied by the first number, and the product remains unchanged.