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Important Formulas: Rational Numbers | Mathematics (Maths) Class 8 PDF Download

Type of Numbers

1. Numbers
N = {1,2,3,4,5……….}
It is the counting numbers

2. Whole number
W= {0,1,2,3,4,5……..}
It is the counting numbers + zero

3. Integers
Z={…-7,-6,-5,-4,-3,-2,-1,0,1,2,3,4,5,6…}

4. Positive integers
Z+= {1,2,3,4,5……..}

5. Negative integers
Z-={…-7,-6,-5,-4,-3,-2,-1}

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:  ½, 4/3 ,5/7 ,1 etc.

Terms

1. Additive Identity/Role of Zero 
Zero is called the identity for the addition of rational numbers. It is the additive identity for integers and whole numbers as well
a + 0 = a

2. Multiplicative identity/Role of one
1 is the multiplicative identity for rational numbers. It is the multiplicative identity for integers and whole numbers as well
a × 1 = a

Properties of Rational Numbers

Closure Property

Important Formulas: Rational Numbers | Mathematics (Maths) Class 8Commutativity Property

Important Formulas: Rational Numbers | Mathematics (Maths) Class 8

Associativity Property

Important Formulas: Rational Numbers | Mathematics (Maths) Class 8

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FAQs on Important Formulas: Rational Numbers - Mathematics (Maths) Class 8

1. What are rational numbers?
Ans. Rational numbers are numbers that can be expressed as a fraction, where the numerator and denominator are both integers. They can be positive, negative, or zero.
2. How do you identify if a number is rational?
Ans. To identify if a number is rational, we check if it can be written as a fraction. If it can, then it is a rational number. For example, numbers like 1/2, -3/4, and 0 are all rational numbers.
3. What are the properties of rational numbers?
Ans. Rational numbers have several properties, including closure under addition, subtraction, multiplication, and division. They can also be compared using inequalities and can be represented on the number line.
4. How do you perform operations on rational numbers?
Ans. To perform operations on rational numbers, we follow the rules of arithmetic. For addition and subtraction, we find a common denominator, add or subtract the numerators, and keep the denominator the same. For multiplication and division, we multiply or divide the numerators and denominators separately.
5. Can irrational numbers be considered as rational numbers?
Ans. No, irrational numbers cannot be considered as rational numbers. Irrational numbers are numbers that cannot be expressed as a fraction and have non-repeating decimal representations. Examples of irrational numbers include √2, π, and e.
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