Here’s how the Rule of 72 works: Divide 72 by your expected annual interest rate (as a percentage, not a decimal). The answer is roughly the number of years it will take for your money to double. For ...

Gemini’s response included a brief description of the “6371” number, which is the Earth’s radius in kilometers. For miles, I ...

The Rule of 72 is a simple calculation tool for investors to use, but it's not necessarily the most accurate. Here are some more precise options to try.

Suppose you have the opportunity to invest in a project that will require a $100 investment today and pay out a single cash flow of $250 in year ...