A number with a negative sign (-) in front of a positive number is called an integer

0 is neither a positive number. Nor is it a negative number

If quantities with opposite meanings appear in a problem, we can use positive numbers and negative numbers to represent them respectively.

Positive numbers, 0, and negative numbers are collectively called rational numbers; positive fractions and negative fractions are collectively called fractions

Classification

Three elements

Add the "-" sign in front of a positive number to get the opposite of the positive number.

Add a "-" sign in front of any number, and the new number represents the opposite of the original number.

Like 2 and -2, 5 and -5, two numbers with only different signs are called opposite numbers.

The opposite of 0 is 0

Add 2 opposite numbers and the sum is 0

The distance between the point representing the number a and the origin on the general number axis is called the absolute value of a, denoted as |a|

The absolute value of a positive number is itself, the absolute value of a negative number is its opposite, and the absolute value of 0 is 0

Comparison of size

To add two numbers with the same sign, take the same sign and add the absolute values.

To add two places with different signs whose absolute values ​​are not equal, take the sign of the addend with the larger absolute value, and subtract the smaller absolute value from the larger absolute value.

If you add a number to 0, you still get this number

Subtracting a number is equivalent to adding the opposite of the number, such as a-b=b (-a)

When a positive number is multiplied by a positive number, the product is positive; when a positive number is multiplied by a negative number, the product is negative; when a negative number is multiplied by a positive number, the product is also negative; the absolute value of the product is equal to the product of the absolute values ​​of the multipliers.

Multiply the two books, the same sign will be positive, and the different signs will be negative, and multiply the absolute values ​​(negative and negative will be positive)

Any number multiplied by 0 gets 0

Odd, negative, even positive (multiplier is not 0)

Dividing by a number that is not equal to 0 is equivalent to multiplying the reciprocal of that number

When dividing two numbers, if they have the same sign, they will get a positive result, if they have different signs, they will get a negative result, and divide the absolute value; 0 divided by any number that is not equal to 0 will get 0