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Rational Number

ICSE · Class 8 · Mathematics

Quick revision notes for Rational Number — ICSE Class 8 Mathematics. Key concepts, formulas, and definitions for last-minute revision.

38 questions28 flashcards5 concepts

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A nested Venn diagram illustrating the relationships between natural numbers (N), integers (Z), rational numbers (Q), and real numbers (R) as subsets of each other.
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Key Topics to Revise

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1. Meaning of Rational Numbers

  • A rational number is a number of the form p/q where p and q are integers and q is not zero.
  • In p/q, p is called the numerator and q is called the denominator.
  • Natural numbers are counting numbers 1, 2, 3, 4, 5, ...
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2. Standard Form and Equivalent Rational Numbers

  • A rational number is in standard form when the numerator and denominator have no common factor other than 1 and the denominator is positive.
  • 3/-5 is not in standard form; its standard form is -3/5.
  • -21/36 is not in standard form because 21 and 36 have a common factor 3.
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3. Addition and Subtraction of Rational Numbers

  • Addition of rational numbers is closed, commutative, and associative.
  • The additive identity for rational numbers is 0.
  • The additive inverse of a rational number is its negative.
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4. Multiplication and Division of Rational Numbers

  • Multiplication of rational numbers is closed, commutative, and associative.
  • Multiplication is distributive over addition and subtraction.
  • The multiplicative identity for rational numbers is 1.

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Full Notes

Key Concepts

A rational number is defined asZero can be written as 0/1A rational number is in standardEquivalent rational numbers are formed byIf a/b = c/d

Frequently Asked Questions

What are the important topics in Rational Number for ICSE Class 8 Mathematics?
Key topics in Rational Number include Mind map showing the hierarchical relationship between different number systems, with rational numbers being the most inclusive, Flowchart showing the process of converting a rational number to standard form, Flowchart showing how to determine if a rational number is positive, negative, or zero based on the signs of its numerator and denominator. These are the concepts ICSE Class 8 examiners draw on most — study them first, then practise related questions.
How to score full marks in Rational Number — ICSE Class 8 Mathematics?
Understand the core concepts first, then work through the 38 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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