These functions express long formulas quickly.
To do arithmetic in Excel, you use formulas. In this lesson, you'll learn how to use a simple formula to find the number of days between two dates, and you'll see why it's very important to type dates so that Excel can recognize them. You'll also learn how to use the prewritten formulas called functions to do other kinds of date math, such as finding out how many days old you are today. In the practice session at the end of the lesson, you'll have a chance to use the formulas you've learned about.