(1) Any power of a positive number is a positive number.

(2) The odd power of a negative number is a negative number; Even the power of negative numbers is positive; Note: When n is positive odd number: (-a)n=-an or (a-b)n=-(b-a)n, when n is positive even number: (-a)n=an or (a-b) n = (b-a) n.

Multiply two numbers, the same sign is positive and the different sign is negative, and the absolute value of multiplication: ("The same sign is positive and the different sign is negative" refers to the case of "multiplying two numbers". If there are more than two factors, you must apply Rule 3) Rule 2: Any number multiplied by 0 will get 0; Rule 3: Multiply several numbers that are not 0. When the number of negative factors is even, the product is positive. When the number of negative factors is odd, the product is negative. Rule 4: Multiply several numbers. If one of the factors is 0, the product is equal to 0.

Multiplication algorithm of rational numbers;

(1) Multiplication commutative law: In general rational number multiplication, two numbers are multiplied, and the position and product of the commutative factor are equal. Namely ab=ba

(2) Multiplication and association law: When three numbers are multiplied, the first two numbers are multiplied first, or the last two numbers are multiplied first, and the products are equal. That is, (ab)c=a(bc).

(3) Multiplication and distribution law: Generally speaking, the multiplication of a number with the sum of two numbers is equivalent to the multiplication of this number with these two numbers respectively, and the products are added. That is, a(b+c)=ab+ac.