When a townmember, Frank, gets evicted from his home he finds a bond issued to his grandfather over 100 years ago. Andy realizes because it was an $100 bond with an 8.5% interest rate compounded annually, Frank might just be rich.
Fifty-three years ago, Jerry's Uncle Leo stiffed Jerry's mother out of $50. Eager to get it back, Jerry's father says, "Do you know what that's worth today in interest alone? $663.45, figured at a conservative 5% interest, compounded quarterly." Morty's calculations are almost accurate, though he does not compound quarterly, and his sum includes the principle, not just the interest.
Fry experiences the effects of compound interest on his savings. He started with 93 cents in his bank account 1,000 years ago, and it has had an average 2.25% interest rate over the 1,000 years. Fry learns that he is now a billionaire.