# Notes Class 9 Mathematics Chapter 1 Number Systems

Please refer to Number Systems Class 9 Mathematics Notes and important questions below. The Class 9 Mathematics Chapter wise notes have been prepared based on the latest syllabus issued for the current academic year by CBSE. Students should revise these notes and go through important Class 9 Mathematics examination questions given below to obtain better marks in exams

## Number Systems Class 9 Mathematics Notes and Questions

The below Class 9 Number Systems notes have been designed by expert Mathematics teachers. These will help you a lot to understand all the important topics given in your NCERT Class 9 Mathematics textbook.

Refer to Chapter 1 Number Systems Notes below which have been designed as per the latest syllabus issued by CBSE and will be very useful for upcoming examinations to help clear your concepts and get better marks in examinations.

1. Rational Numbers
2. Irrational Numbers
3. Real Numbers and their Decimal Expansions
4. Operations on Real Numbers
5. Laws of Exponents for Real Numbers
Natural numbers are – 1, 2, 3, ……………. denoted by N.
Whole numbers are – 0, 1, 2, 3, ……………… denoted by W.
Integers – ……. -3, -2, -1, 0, 1, 2, 3, ……………… denoted by Z.

Rational numbers – All the numbers which can be written in the form r / s p / q, are called rational numbers where p and q are integers.
Irrational numbers – A number s is called irrational, if it cannot be written in the form p / q where p and q are integers and
The decimal expansion of a rational number is either terminating or non-terminating recurring. Thus we say that a number whose decimal expansion is either terminating or nonterminating recurring is a rational number.
The decimal expansion of a irrational number is non terminating non-recurring.
All the rational numbers and irrational numbers taken together.
Make a collection of real number.
A real no is either rational or irrational.
• If r is rational and s is irrational then r+s, r–s, r.s are always irrational numbers but r/s may be rational or irrational.
Every irrational number can be represented on a number line using Pythagoras theorem.
Rationalization means to remove square root from the denominator.