1. Multiply two numbers, the same sign is positive, the different sign is negative, and the absolute value is multiplied. For example: (-5)×(-3)= 15 (-7)×4=-28.

2. Any number multiplied by 0 will get 0.

3. Two rational numbers whose product is 1 are reciprocal. For example,-1/2 and -2.

4. When several numbers except 0 are multiplied, when the number of negative factors is even, the product is positive; When the negative factor is odd, the product is negative. Example: The product of 2 ×3 × 4×(-5) is negative, while the product of (-2)×(-3)× (-4)× (-5) is positive.

5. Multiply several numbers. If one of the factors is 0, the product is equal to 0. [ 1]

separate

1. Divided by a number that is not equal to 0 is equal to multiplying the reciprocal of this number.

2. Divide two numbers, the same sign is positive and the different sign is negative, and divide by the absolute value.

Divide 3.0 by any number that is not equal to 0 to get 0. [ 1]

note:

0 cannot be divided under any circumstances.

Mixed operation

The mixed operation of addition, subtraction, multiplication and division of rational numbers, if there is no bracket to indicate what operation to do first, will be carried out in the order of "multiplication and division first, then addition and subtraction".

The above is from Baidu Encyclopedia