In this section, you will use strings and numbers to make a useful program. This program calculates how much money you will pay on a loan with a certain interest rate.

If you borrow an amount of money X, at an annual rate R, and you pay it back over N months, there is an equation to calculate the monthly payment. It is a big, ugly equation:

This is a huge pain to enter into a calculator.

It is not very much fun to enter into Python, either, so just this once, you can copy and paste the calculation from the program below.

We are going to calculate a loan of $10,000 at 5.25 percent, for 72 months.

Create a new Python file, type the following and run it:

You should see this output:

This program calculates how much money you will pay on a loan.

If you borrow 10000 dollars and pay it back over 72 months at an

annual interest rate of 5.25 percent, your monthly payment will be:

162.211537477

Your total payable will be:

11679.2306983

Congratulations! You have written a program that can do something useful for you. In the next section, we will modify it to make it a little more powerful.