CBSE Class 9 Maths Number System

All the natural numbers, whole numbers and integers are included in rational numbers.
When a rational number is expressed as a decimal, then either the decimal will terminate or there will be a predictable pattern of digits.
Zero is neither positive nor negative
Rational numbers are the numbers of arithmetic: The whole numbers, fractions, mixed numbers, and decimals; together with their negative images.

A non-terminating repeating decimals are irrational numbers.
There are infinitely many rational and irrational numbers between two numbers.
An irrational number cannot be expressed in the p/q form.

The sum or difference of a rational number and an irrational number is an irrational number,
The product or quotient of a non-zero rational number with an irrational number is irrational.
If we add, subtract, multiply or divide two irrational numbers we may or may not get an irrational number,
To rationalize the denominator of 1/ a+b root x, we multiply it by a -b root x / a - b root x where 'a' and 'b' are integers.
To rationalize the denominator of root x + root y , we multiply it by root x - root y / root x - root y.

Statement of the laws of exponents and simplify expressions using the same.

Whole numbers, integers, rational numbers and irrational numbers can be represented on the number line.
There is one to one correspondence between the set of real numbers and the set of point on the number line.
This means corresponding every point on the number line, there is one and only one real number