## Compound InterestP is the principal (the money you start with, your first deposit)r is the annual rate of interest as a decimal (5% means r = 0.05) n is the number of years you leave it on deposit A is how much money you've accumulated after n years, including interest. If the interest is compounded once a year: A = P(1 + r) If the interest is compounded q times a year: A = P(1 + r/q) Back to the story
about how that last formula could apply to cockroaches. And two formulas about annuities: amount an of annuity and the present value of an annuity. |