For my windfall inheritance, I have chosen an initial amount of $20,000 (P for principal), and a reasonable interest rate of 8%. I will invest this money for 20 years, allowing for compound interest to be calculated monthly. Using the compound interest formula (A = P(1 r/n)^(nt)), the total amount of money that will grow in my chosen time frame is: A = $20,000(1 0.08/12)^(12*20) = $78,053.29 The interest earned during this period is: $78,053.29 - $20,000 = $58,053.29 If I had an additional 10 years to let my investment grow, the final investment amount would be calculated as follows: A = $20,000(1 0.08/12)^(12*30) = $158,832.63 The interest earned during this period is: $158,832.63 - $20,000 = $138,832.63