MathematicsClass 8Rational Numbers

Introduction to Rational Numbers

Understanding numbers that can be expressed in the form p by q where p and q are integers and q is not equal to zero.

Class 8 · MathematicsCBSE & ICSE SOF IMO

Definition

A rational number is a number that can be expressed in the form p/q, where p and q are integers and q is not equal to zero. They include all integers, fractions, and terminating or repeating decimals. Understanding them helps extend our number system beyond whole numbers and fractions.

Key formula

r = p/q where p, q in Z and q != 0

Worked examples

1

3/4 is a rational number because both 3 and 4 are integers and the denominator is not zero.

2

-5 can be written as -5/1, making it a rational number.

3

0 is a rational number because it can be expressed as 0/1.

Common mistakes

  • Thinking that a fraction with a zero denominator like 5/0 is a rational number.
  • Assuming whole numbers are not rational numbers.
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