CBSE · Class 8 · Mathematics · Chapter 13

Algebra Play

Explore algebraic expressions, patterns, identities and equation-solving through puzzles and reasoning.

10 lessons 55 min
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Lessons in this chapter

  1. 1Think of a Number TricksUse algebra to uncover why constant-result number tricks work and design new tricks that are guaranteed to succeed.
  2. 2Date-Guessing Tricks and Creating Your Own TricksUse variables and place value to explain, decode, and redesign a date-guessing algebra trick.
  3. 3Number Pyramids — Finding Missing NumbersSolve number pyramids by adding upward, subtracting backward, and forming equations for missing entries.
  4. 4Patterns in Number PyramidsGeneralise number pyramids with algebraic top expressions and explore their connection with the Virahāṅka–Fibonacci sequence.
  5. 5Calendar Magic and Algebra GridsUse calendar structure and shape grids to turn visual patterns into equations, formulas, and solvable tricks.
  6. 6The Largest ProductOptimise digit-placement products by systematic comparison, place-value algebra, and a general proof.
  7. 7Decoding Divisibility TricksUse place-value algebra to prove divisibility patterns involving reversed, cycled, and repeated digits.
  8. 8Algebraic Story PuzzlesModel repeated processes, animals, ages, and sharing puzzles with equations and context-aware checks.
  9. 9Algebra in Money, Patterns, and Repeated ProcessesApply algebra to profit models, odd-number identities, and repeated doubling-and-fee processes.
  10. 10Chapter Summary and PracticeReview the chapter's algebraic tools through mixed examples, error analysis, proof, modelling, and cumulative practice.
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