Mathematics · Class 8
Comparing Quantities
Discount, sales tax, compound interest, and percentage increase-decrease.
4 sections15–25 min read6 MCQs · 2 examples
Chapter Overview
Class 8 extends comparing quantities to compound interest, discount, tax (GST), and depreciation — real financial literacy for Indian students.
Compound Interest
Amount
A = P(1 + R/100)ⁿ
CI
CI = A − P
Half-yearly
Rate and time adjusted for periods
Discount and Tax
- Discount = Marked Price − Sale Price
- Discount% = (Discount/MP) × 100
- GST added on taxable value
Depreciation
Value decreases by fixed % per year — same formula as CI but subtracted.
Solved Examples
Step-by-step solutions — read each step before checking the final answer.
Example 1: CI
Find CI on ₹10,000 at 10% for 2 years.
- 1A = 10000(1.1)² = 12100
- 2CI = 12100 − 10000
Answer
₹2,100
Example 2: Discount
MP ₹800, discount 15%. Find SP.
- 1Discount = 800×15/100 = 120
- 2SP = 800 − 120
Answer
₹680
Key Points to Remember
- ✓ CI > SI for same P, R, n > 1
- ✓ GST may be CGST + SGST
- ✓ Depreciation reduces asset value
Exam Tips
- • State formula and substitute
- • For half-yearly, double periods halve rate
Practice MCQs — Comparing Quantities
Test your understanding with topic-wise multiple choice questions. Explanations appear after each answer.
Question 1 of 6Score: 0/0
CI on same sum for 2 years is ___ SI: