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NCERT Solutions for Ganita Prakash (Part 1) Chapter 4 Expressions using Letter-Numbers

Updated on 2026-09-05

About this chapter

A letter used in place of a number is a letter-number ; an expression built from letter-numbers and numbers is an algebraic expression . The multiplication sign is dropped: 4 × n is written 4n, with the number first. Swapping, grouping, opening brackets and the distributive property work exactly the same for algebraic expressions as for arithmetic ones. Like terms (5c, 3c, 10c) can be added into one term; unlike terms (18c, 11d) cannot. Expressions let us describe patterns — matchstick steps, calendar squares, saree borders, traffic signals — and, more importantly, prove that the pattern always holds. A formula is read both ways: from a situation to an expression, and from an expression back to a situation.

  • The Notion of Letter-Numbers
  • –85Section 4.1 The Notion of Letter-Numbers
  • –86Section 4.2 Revisiting Arithmetic Expressions
  • Omission of the Multiplication Symbol
  • –90Section 4.4 Simplification of Algebraic Expressions
  • –93Section 4.4 Simplification of Algebraic Expressions
  • –94Section 4.4 Simplification of Algebraic Expressions
  • –95Section 4.4 Simplification of Algebraic Expressions
  • –96Section 4.5 Pick Patterns and Reveal Relationships
  • –97Algebraic Expressions to Describe Patterns
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Exercises

  1. In-text Questions — The Notion of Letter-Numbers Page 81
  2. In-text Questions — The Notion of Letter-Numbers Page 82
  3. In-text Questions — The Notion of Letter-Numbers Page 83
  4. –85Section 4.1 The Notion of Letter-Numbers — Figure it Out Page 84
  5. –86Section 4.2 Revisiting Arithmetic Expressions — In-text Questions Page 85
  6. Mind the Mistake, Mend the Mistake — Omission of the Multiplication Symbol Page 87
  7. –90Section 4.4 Simplification of Algebraic Expressions — In-text Questions Page 88
  8. –93Section 4.4 Simplification of Algebraic Expressions — In-text Questions Page 91
  9. –94Section 4.4 Simplification of Algebraic Expressions — Figure it Out Page 93
  10. –95Section 4.4 Simplification of Algebraic Expressions — Mind the Mistake, Mend the Mistake Page 94
  11. –96Section 4.5 Pick Patterns and Reveal Relationships — Formula Detective Page 95
  12. –97Algebraic Expressions to Describe Patterns — In-text Questions Page 96
  13. –99Patterns in a Calendar — In-text Questions Page 97
  14. –101Matchstick Patterns — In-text Questions Page 100
  15. –105Section 4.5 Pick Patterns and Reveal Relationships — Figure it Out Page 102
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