Deep Analysis: The Mechanics of Compound Interest
Compound interest is the process where the interest you earn begins generating its own interest. Albert Einstein famously referred to it as the "Eighth Wonder of the World," because of its ability to create an exponential growth curve over long timelines.
The Frequency Multiplier Effect
The standard formula is: A = P (1 + r/n)^(n*t), where 'n' is the number of times interest is compounded per year. The higher the frequency, the greater your final return. A 10% rate compounded daily will yield significantly more absolute profit than a 10% rate compounded annually on the exact same principal.
The Rule of 72
Investors use a mental model called the "Rule of 72" to instantly estimate compounding effects. If you want to know how many years it will take for your money to double, simply divide 72 by your annual interest rate. For example, at an 8% return, your money will double in exactly 9 years (72 ÷ 8 = 9).