There are three simple steps to determining the interest liability on a loan note, so you'll know the total amount you're paying.

The formula for calculating simple interest in a savings account is Interest = P * R * T. Multiply the account balance by the interest rate by the time period.

The Rule of 72 is a shortcut or rule of thumb used to estimate the number of years required to double your money at a given annual rate of return and vice versa.

To calculate interest-only loan payments, multiply the loan balance by the annual interest rate, and divide it by the number of payments in a year.

Fact checked by Heather van der Hoop Shopping for a new or used car? Use our free car loan calculator to see your monthly payment and the total interest cost over the life of the loan. Key Takeaways ...