Chapter 3
The Mathematics of Money

Applet 3. Finance Calculator

A calculator to solve formulas involving loans and investments. The calculator enables the user to investigate the effect of varying parameters in the following financial formulas: simple interest, compound interest, systematic savings, and general loan. In each case, the calculator will solve for whichever one of the fields is left selected, using the data in the other fields.


  1. Select the financial formula you want to study from the tabs at the top of the calculator. The formula you will be working with appears at the top of the card.
  2. Enter data into all but one of the fields.
  3. When you click on the remaining field, the calculator will fill in the field with the appropriate value.
  4. For example, if you enter data under "simple interest" for the future value of your savings, the rate of interest, and the amount of the deposit, then when you click on the "time in years" of the investment, the field will fill in with the time it takes for your initial investment to reach the desired final value.
  5. You can change the values in one field and then click on another field, to see how changes to one parameter affect another. For example, after having calculated how long it would take for a particular savings scheme to accumulate $10,000, you might change the "future value" to $15,000 and then click on the "amount of deposit" field to see how much more you would need to save regularly to reach $15,000 in the same time. Or you might click on the interest rate to see how high interest rates would have to be to make your savings reach $15,000 instead of $12,000.