Question

At what rate of interest will a sum of money double itself in 5 years​

Answer 1

13.94%

There are tons of calculators out there that can do this but usually they calculate what you have in the bank after so many years and at what interest rate. These calculators usually run using compound interest, compounded monthly. (Each month, interest is calculated, added to the principal and then calculated. Simple interest is compounded yearly.)

To answer your question, one needs to know if the interest is simple, computed monthly, or continuously. To get 13.94% I used monthly which is what your bank is going to use. Occasionally they will use compounded continuously but the difference these days of low interest will not buy you a Starbucks latte.

Rates that increase a sum in five years these days is usually a description of what is happening to your credit card debt. Don’t do that. Pay it off every month and eat day old bread before you let credit card debt eat your paycheck.