1, add two numbers with the same sign, take the same sign as the addend, and add the absolute values.

2. Add two numbers with different signs. If the absolute values are equal, the sum of two numbers with opposite numbers is 0; If the 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.

3. Add two numbers with opposite numbers to get 0.

Rational number subtraction operation:

Subtracting a number is equivalent to adding the reciprocal of this number, that is, the subtraction of rational numbers is converted into addition.

Extended data:

Properties of addition operation

From additive commutative law's associative law, it can be concluded that when several addends are added, the positions of addends can be exchanged at will; Or add a few addends first and then add them with other addends, and the sum remains the same.

For example: 34+72+66+28 = (34+66)+(72+28) = 200.

Subtraction operation property

(1) A number minus the sum of two numbers is equal to subtracting each addend in the sum from this number in turn.

For example:134-(34+63) =134-34-63 = 37.

(2) A number minus the difference between two numbers is equal to this number minus the minuend in the difference first and then minus the minuend.

For example: 100-(32-15) =100-32+15 = 68+15 = 83.