Shortcut Trick Identify Leap Year: 2024 is a leap year (366 days). Total days = 20 (Feb) + 31 (Mar) + 10 (Apr) = 61 days. Interest Calculation: Interest = (3000 × 6 × 61/366) / 100 Since 6 × 61 = 366, Interest = 3000 / 100 = 30. ∴ The correct answer is ₹30. Alternate Method Given: Principal (P) = ₹3,000 Rate (R) = 6% per annum Time period = 9 February 2024 to 10 April 2024 Formula Used: Simple Interest (SI) = (P × R × T) / 100 Calculations: ⇒ Number of days in February = 29 − 9 = 20 days (2024 is a leap year) ⇒ Number of days in March = 31 days ⇒ Number of days in April = 10 days ⇒ Total Days = 20 + 31 + 10 = 61 days ⇒ Time (T) in years = 61 / 366 years ⇒ SI = (3000 × 6 × (61/366)) / 100 ⇒ SI = (3000 × 6 × 61) / (100 × 366) ⇒ SI = (3000 × 366) / (100 × 366) ⇒ SI = 3000 / 100 ⇒ SI = ₹30 ∴ The correct answer is ₹30. Related Concepts: Leap Year Calculation A year is a leap year if it is divisible by 4. If it is a century year (ending in 00), it must be divisible by 400. Leap years have 366 days. Day Counting Rule In banking and financial interest calculations, normally the day of deposit is excluded and the day of withdrawal is included (or vice versa). Simple Interest vs Compound Interest Simple interest is calculated only on the principal, while compound interest is calculated on the principal plus accumulated interest from previous periods.