1. **State the problem:** Calculate the compound interest earned on an investment of 800 at an interest rate of 10% per annum over 2 years. 2. **Formula used:** Compound interest is calculated using the formula: $$A = P \left(1 + \frac{r}{100}\right)^n$$ where $A$ is the amount after $n$ years, $P$ is the principal, $r$ is the annual interest rate, and $n$ is the number of years. 3. **Calculate the amount $A$ after 2 years:** $$A = 800 \left(1 + \frac{10}{100}\right)^2 = 800 \left(1 + 0.1\right)^2 = 800 \times 1.1^2$$ 4. **Evaluate $1.1^2$:** $$1.1^2 = 1.21$$ 5. **Calculate $A$:** $$A = 800 \times 1.21 = 968$$ 6. **Calculate the interest earned:** $$\text{Interest} = A - P = 968 - 800 = 168$$ **Final answer:** The interest earned after 2 years is **168**.