Specifically, I was curious about how Harvard's endowment has grown from its initial £780 in 1638, so I asked Google to calculate compound interest for me. A variety of searches all yield a reasonable formula which is then calculated to be quite wrong. For example: {calculate the present value of $100 compounded annually for 386 years at 3% interest} yields $0.736. {how much would a 100 dollar investment in 1638 be worth in 2025 if invested} yields $3,903.46. {100 dollars compounded annually for 386 years at 3 percent} yields "The future value of the investment after 386 years is approximately $70,389." And my favorite: {100 dollars compounded since 1638} tells me a variety of outcomes for different interest rates: "A = 100 * (1 + 0.06)^387 A ≈ 8,090,950.14 A = 100 * (1 + 0.05)^387 A ≈ 10,822,768.28 A = 100 * (1 + 0.04)^387 A ≈ 14,422,758.11"
How can we be so reasonable and yet so bad!?