When you need to perform standard calculations in your worksheets, use Excel's built-in functions. The functions are predefined calculations that you drop into your formulas and provide with the data they need.
You can enter functions using either the Function drop-down list in the Editing group of the Home tab of the Ribbon or by using the controls in the Function Library group on the Formulas tab. We'll look at each approach in turn. But first, we'll examine the components of a function so that you know what's what.
In Excel, a function has a name written in capitals followed by a pair of parentheses. For example:
SUM(). This widely used function ...