Compound Interest Cheat Sheet
Compound interest is the eighth wonder of the world. He who understands it, earns it; he who doesn't, pays it. It's the process of earning interest on both the initial principal and the accumulated interest from previous periods.
Core Principles
- Interest on Interest: The core concept is earning returns on your returns.
- Exponential Growth: Compounding leads to accelerated wealth accumulation over time.
- Time is Your Ally: The longer your money compounds, the greater the impact.
- Frequency Matters: More frequent compounding (daily vs. annually) yields higher returns.
- Reinvestment is Key: Ensure interest earned is added back to the principal.
- Power of Starting Early: Even small amounts invested early can grow significantly.
Formulas
- $A = P(1 + r/n)^{nt}$
- Where:
- A = the future value of the investment/loan, including interest
- P = the principal investment amount (the initial deposit or loan amount)
- r = the annual interest rate (as a decimal)
- n = the number of times that interest is compounded per year
- t = the number of years the money is invested or borrowed for
Quiz
- What is the primary driver of compound interest growth?: Time and reinvestment of earnings
- If interest is compounded more frequently (e.g., daily vs. annually), what happens to the final amount?: It increases slightly
- Which scenario best illustrates the power of compound interest?: Investing a small amount early and consistently
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