Simple and Compound Interest – Speed Tricks
Solve interest questions quickly using shortcut formulas and growth factor method.
Simple Interest Formula
SI = (P × R × T) / 100
Compound Interest Formula
Amount = P × (1 + R/100)T
Shortcut Trick 1 (1 Year)
Q: ₹1000 at 10% for 1 year
Answer:
SI = ₹100
Shortcut Trick 2 (2 Years Difference)
Formula:
CI − SI = (P × R²) / 10000
Example:
1000 × 10² / 10000 = ₹10
Growth Factor Trick
Q: ₹1000 at 20% for 2 years
Method:
1000 × (1.2)² = 1000 × 1.44 = ₹1440
Exam Level Questions
1. ₹5000 at 10% for 2 years (CI)?
Answer: ₹6050
2. ₹2000 at 5% for 1 year (SI)?
Answer: ₹100
3. ₹1000 becomes ₹1210 in 2 years → rate?
Answer: 10%
Common Mistake
Students use SI formula for compound interest questions.
Speed Tip
Use growth factor (1 + R/100) instead of step-by-step multiplication.
Shaktimatha Learning
Speed Maths • Bank Exam Preparation
Speed Maths • Bank Exam Preparation
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