6. Calculating the Number of Periods At 6.25 percent interest, how long does it take to double your money? To quadruple it? . 7. Calculating Present Values Imprudential, Inc., has an unfunded pension liability of $425 million that must be paid in 20 years. To assess the value of the firm's stock, financial analysts want to discount this liability back to the present. If the relevant discount rate is 5.9 percent, what is the present value of this liability