Project Summary: One of the things we are studying this week is percent. Percentages have many applications in consumer math and the more you understand about percent and percentages, the more informed decisions you can make. For example, the price of a stock is one thing to consider when investing, but the change in value over time might be an even more important thing to consider. We will use percent change to investigate this topic. Percent and Percent Change Companies can be privately or publicly held. The main difference is that publicly held companies have shares that can be traded publicly on the stock market with stock prices going up and down over time.