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Rational Number — Revision Notes

ICSE · Class 8 · Mathematics

Rational Number revision notes for ICSE Class 8 Mathematics: 4 topics in quick points. Part of the ICSE Class 8 Mathematics syllabus.

38 questions28 flashcards9 formulas & key relations5 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 Meaning of Rational Numbers, Standard Form and Equivalent Rational Numbers, Addition and Subtraction of Rational Numbers, Multiplication and Division of Rational Numbers. Study these first, then practise questions on each for Class 8 exams.
How should I revise Rational Number for Class 8 exams?
Learn the core ideas first, then work through the 38 practice questions on Rational Number. Revise 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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All ICSE Class 8 Mathematics Revision Notes

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