A dollar invested at a 10% return will be worth $1.10 in a year. Invest that $1.10 and get 10% again, and you'll end up with $1.21 two years from your original investment. The first year earned you only $0.10, but the second generated $0.11. This is compounding at its most basic level: gains begetting more gains. Increase the amounts and the time involved, and the benefits of compounding become much more pronounced.
Compound interest can be calculated using the following formula:
FV = PV (1 + i)^N
FV = Future Value (the amount you will have in the future)
PV = Present Value (the amount you have today)
i = Interest (your rate of return or interest rate earned)
N = Number of Years (the length of time you invest)
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