What is compound interest?

• A. Interest calculated only on the initial principal
• B. Interest calculated on the initial principal and accumulated interest
• C. Interest that remains constant over time
• D. Interest that decreases with each payment

Answer: (B)

Compound interest refers to the method of calculating interest where interest is applied not only to the initial principal amount but also to any interest that has been previously added to that principal. This means that over time, as interest is earned on the accumulated interest, the amount of interest earned grows at an increasing rate. This can lead to significantly larger returns over time compared to simple interest, which is only calculated on the initial principal.

Understanding the mechanics of compound interest is essential for effective personal finance management. For example, if you invest money in a savings account that offers compound interest, your investment grows more quickly than it would in a scenario where only simple interest is applied, as every period's interest calculation builds upon the last. This compounding effect is often referred to as "interest on interest," which is a powerful concept in both saving and investing.