Compound Interest Basics | Simple & Compound Interest Aptitude Practice | Kuriloo

The process where asset earnings are reinvested to generate additional earnings over subsequent time blocks.

The total value of an investment after time T, calculated using the baseline compound formula: $A = P \cdot (1 + R/100)^T$.

Unlike simple interest formulas which find the interest directly, the standard compound interest formula gives you the total maturity amount first.
To isolate the absolute Compound Interest (CI) earned, you must subtract the original Principal from the final Maturity Amount: $CI = A - P$.

Rule of 72 Shortcut: To quickly estimate how many years it will take for your investment to double under compound interest, divide 72 by the annual interest rate ($T \approx 72 / R$).

Q: Why does compound interest grow faster than simple interest?

A: Because your underlying balance grows every year, meaning the interest calculation is based on a larger sum each time.

Foundational exponential growth calculation.

Problem QueryA business owner invests $1000 at a 10% annual compound interest rate for 2 years. Calculate the absolute compound interest earned.

Step-By-Step Solution Path

Identify the core variables: Principal (P) = 1000, Rate (R) = 10, Time (T) = 2.

Apply the maturity formula: $A = 1000 \cdot (1 + 10/100)^2$.

Simplify the compounding factor: $A = 1000 \cdot (1.1)^2 = 1000 \cdot 1.21 = $1210$.

Subtract the principal to isolate the interest earned: $CI = 1210 - 1000 = $210$.

Analytical Hint: Calculate the total final value first, then subtract your original principal to see just the interest profit.

Practice calculating maturity balances and isolating compound interest returns.

Q1. An asset of $5000 is invested at a 20% annual compound interest rate. What is its total value after 2 years?