The simple interest formula, i = p*r*t, is an important linear equation and understanding it is a fundamental skill to help you manage your finances.

• p = principal
• r = interest rate written as a decimal
• t = time in years
• i = amount of interest earned (or owed)

If you know two of the three variables, you can solve for the unknown variable.

Now, the amount of money in an account after simple interest has been earned is given by the formula:

A = principal + interest earned

or

A = p + p*r*t

Choose your principal and time and solve for the rate.