# NCERT Class 9 Maths Formula CBSE Board Sample Problems Part 1 (For CBSE, ICSE, IAS, NET, NRA 2022)

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CBSE Class 9 Math՚s Summary

This pdf list all the Class 9 CBSE math՚s formula in a concise manner to help the students in revision and examination as per NCERT syllabus

## 1. Number System

 S. no Type of Numbers Description 1 Natural Numbers It is the counting numbers 2 Whole number W It is the counting numbers + zero 3 Integers 4 Positive integers 5 Negative integers 6 Rational Number A number is called rational if it can be expressed in the form p/q where p and q are integers (q > 0) .Example: etc. 7 Irrational Number A number is called rational if it cannot be expressed in the form p/q where p and q are integers (q > 0) .Example: etc. 8 Real Numbers All rational and all irrational number makes the collection of real number. It is denoted by the letter R 9 What is zero Zero number definitionZero is a number used in mathematics to describe no quantity or null quantity. It is also used as placeholder digit in many numbersThe modern O symbol was invented in India in the 6th century, used later by the Persians and Arabs and later in Europe.Important facts about zero(1) Zero is a number but it is neither positive nor negative number.So, it is not included in the set of positive number nor negative numbers.But it is included in the set of non-negative numbers(2) Zero is an even number(3) Zero is not a prime nor a composite number.It cannot be prime because it has an infinite number of factors and cannot be composite because it cannot be expressed by multiplyingprime numbers (0 must always be one of the factors)

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