Simple & Compound Interest – Tricks & Tough Problems
Master interest calculations using shortcut tricks for bank exams.
1. Important Concepts
- Simple Interest (SI) = (P × R × T) / 100
- Compound Interest (CI) = P(1 + R/100)^T
- Amount = Principal + Interest
- Difference between CI and SI
2. Speed Tricks
- For 2 years: CI − SI = (P × R²) / 10000
- Use percentage growth formula
- Memorize square values
- Convert percentage into fraction
3. Tough Problems
Q1: Find SI on ₹2000 at 10% for 2 years
Solution:
SI = (2000 × 10 × 2)/100 = ₹400
Q2: Find CI on ₹1000 at 10% for 2 years
Solution:
Amount = 1000 × (1.1)^2 = 1210
CI = 1210 − 1000 = ₹210
Q3: Find difference between CI and SI for ₹1000 at 10% for 2 years
Solution:
Difference = (1000 × 10²)/10000 = ₹10
Q4: Find amount if ₹5000 is invested at 20% for 2 years (CI)
Solution:
Amount = 5000 × (1.2)^2 = 5000 × 1.44 = ₹7200
Q5: At what rate will ₹1000 become ₹1210 in 2 years (CI)?
Solution:
1210 = 1000 × (1 + R/100)^2
(1 + R/100)^2 = 1.21
R = 10%
4. Exam Tips
- Memorize CI shortcuts for 2 and 3 years
- Use growth factor method
- Avoid full multiplication
- Practice percentage-based problems
Shaktimatha Learning
Quant • Interest • Bank Exam Preparation
Quant • Interest • Bank Exam Preparation
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