In this section, we apply the material of this chapter to localize a retirement calculator. The program calculates whether or not you are saving enough money for your retirement. You enter your age, how much money you save every month, and so on (see Figure 5.4).
The text area and the graph show the balance of the retirement account for every year. If the numbers turn negative toward the later part of your life and the bars in the graph appear below the x axis, you need to do something—for example, save more money, postpone your retirement, die earlier, or be younger.