Class 8 Maths – Chapter 8

Comparing Quantities

Mind Map + Easy Memory Tricks

🧠 Chapter Mind Map

• Percentages (%)
  • Fraction → %
  • Decimal → %
  • Finding % of a number
• Profit & Loss
  • Cost Price (CP)
  • Selling Price (SP)
  • Profit = SP − CP
  • Loss = CP − SP
• Discount
  • Marked Price (MP)
  • Discount = MP − SP
  • Discount %
• Simple Interest
  • Principal (P)
  • Rate (R)
  • Time (T)
  • Amount = P + SI

🎯 Easy Memory Tricks

1️⃣ Percentage Trick:

% = Per 100

👉 Always divide by 100

2️⃣ Profit / Loss Trick:

SP > CP → Profit 😊

SP < CP → Loss 😟

3️⃣ Discount Trick:

MP − SP = Discount

(Marked price is always the bigger number)

4️⃣ Simple Interest Formula Trick:

P × R × T ÷ 100

👉 Remember as PRT / 100

5️⃣ Amount Trick:

Amount = Principal + Interest

📝 Exam Writing Tips

• Write formula first (compulsory)
• Show calculation steps
• Underline or box the final answer
• Use ₹ symbol correctly