Using the Insert Function Button

Excel provides more than 300 built-in functions. In order to use a function, however, you need to type its name in exactly.

To use the Insert Function feature, choose Formulas> Function Library> Insert Function. However, formula pros skip straight to the action by clicking the fx button that appears just to the left of the formula bar. (Or, they press the Shift+F3 shortcut key.)

No matter which approach you use, Excel displays the Insert Function dialog box, which offers three ways to search for and insert any of Excel's functions.
 

The Insert Function dialog box lets you quickly find the function you need. You can choose a category that seems likely to have the functions you are interested in.
You can also try to search by entering keywords in the "Search for a function" box. Either way, when you click one of the functions in the list, Excel presents you with a description of the function at the bottom of the window.

1. If you are looking for a function, the easiest way to find one is to choose a category from the "Or select a category" drop-down list. For example, when you select the Math and Trig category, you see a list of functions with names like SIN( ) and COS( ), which perform basic trigonometric calculations.
2. If you choose the Most Recently Used category, you'll see a list of functions you've recently picked from the ribbon or the Insert Function dialog box.
3. If you're really ambitious, you can type a couple of keywords into the "Search for a function" text box. Next, click Go to perform the search. Excel gives you a list of functions that match your keywords.

When you spot a function that looks promising, click it once to highlight its name. Excel then displays a brief description of the function at the bottom of the window. For more information, you can click the "Help on this function" link in the bottom-left corner of the window. To build a formula using this function, click OK.
 

Depending on the function you're using, Excel may make a (somewhat wild) guess about which arguments you want to supply. For example, if you use the Insert Function window to add a SUM( ) function, then you'll see that Excel picks a nearby range of cells. If this isn't what you want, just replace the range with the correct values.

Now you can finish creating your formula by using the Function Arguments dialog box, which includes a text box for every argument in the function. It also includes a help link for detailed information about the function bottom-left corner of the window.

To complete your formula, follow these steps:

1. Click the text box for the first argument.
   A brief sentence describing the argument appears in the Function Arguments dialog box.
   Some functions don't require any arguments. In this case, you don't see any text boxes, although you still see some basic information about the function.
2. Enter the value for the argument.
   If you want to enter a literal value (like the number 52), type it in now. To enter a cell reference, you can type it in manually, or click the appropriate cell on the worksheet. To enter a range, drag the cursor to select a group of cells. Skip directly to step 4.
3. You may need to move the Function Arguments dialog box to the side to expose the part of the worksheet you want to click. The Collapse Dialog Box icon (located to the immediate right of each text box) is helpful since clicking it shrinks the window's size. This way, you'll have an easier time selecting cells from your worksheet. To return the window to normal, click the Expand Dialog Box icon, which is to the right of the text box.
4. Repeat step 2 for each argument in the function.
   As you enter the arguments, Excel updates the formula automatically.
5. Once you've specified a value for every required argument, click OK.
   Excel closes the window and returns you to your worksheet.