1, rational number:

Rational number is the collective name of integer (positive integer, 0, negative integer) and fraction, and it is the set of integer and fraction. Integers can also be regarded as fractions with a denominator of one. Real numbers that are not rational numbers are called irrational numbers, that is, the fractional part of irrational numbers is infinite cyclic numbers.

It is one of the important contents in the field of number and algebra, and it is widely used in real life. It is the basis for continuing to learn real numbers, algebraic expressions, equations, inequalities, rectangular coordinate systems, functions, statistics and other mathematical contents and related disciplines.

2, irrational number:

Irrational number, also known as infinite acyclic decimal, cannot be written as the ratio of two integers. If written in decimal form, there are infinitely many digits after the decimal point, which will not cycle. Common irrational numbers include the square root, π and E (the latter two are transcendental numbers) of incomplete square numbers.

Addition of rational numbers:

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.

4. Adding a number to 0 still gets this number.

You can add two opposite numbers first.

6. Numbers with the same sign can be added first.

7. Numbers with the same denominator can be added first.

8. If several numbers can be added to get an integer, they can be added first.