Class 8 Maths – Chapter 7
Cubes & Cube Roots

Mind Map + Easy Learning Tricks

🧠 Chapter Mind Map (One-Page View)

• Cubes
  • Meaning: n × n × n
  • Examples: 2³ = 8, 3³ = 27
  • Positive number → Positive cube
  • Negative number → Negative cube
• Perfect Cubes
  • Numbers like: 1, 8, 27, 64, 125
  • Prime factors appear in groups of 3
• Cube Roots
  • Reverse of cube
  • ∛64 = 4
  • ∛(−125) = −5
• Prime Factorisation
  • Group factors in 3s
  • One factor from each group = cube root

✨ Easy Tricks to Learn Cubes

• Trick 1: Last digit trick
  Cube of numbers ending with:
  1 → 1, 2 → 8, 3 → 7, 4 → 4, 5 → 5
• Trick 2: Cube of multiples of 10
  10³ = 1000, 20³ = 8000
• Trick 3: Negative numbers
  (−a)³ = −(a³)

🎯 Easy Tricks for Cube Roots

• Trick 1: Last digit method
  Example: ∛1331
  Ends with 1 → answer ends with 1
• Trick 2: Number of digits
  4-digit cube → 2-digit cube root
• Trick 3: Perfect cube check
  If factors are not in 3s → NOT a perfect cube

🧩 Mnemonics (Memory Shortcuts)

• Perfect cubes till 5:
  1-8-27-64-125
  👉 "I Ate 27 Large Burgers"
• Cube root steps:
  F-G-P → Factor → Group → Pick

📝 Exam Tips

• Always write prime factorisation clearly
• Show grouping of 3 factors
• Underline final answer
• Negative sign is compulsory if given

🌟 Designed for kids by Shaktimatha Learning | CBSE Class 8