Functions can be entered manually, but to do this you need to know the name of the function and the syntax for the arguments.
In Excel 2002, Excel 2003, Excel 2007, and Excel 2010, if you enter the name of the function, syntax-specific help is displayed to help you complete the parameters. Programmers who work with Microsoft Visual Basic for Applications are already familiar with this type of help, which displays a ScreenTip as soon as you enter the function name and the opening parenthesis (see Figure 4-6). Each argument in turn is shown in bold as you enter the individual parameters.
Figure 4-6. The ScreenTip for the IF() function. ...