## Annotating Formulas

You can attach notes to cells by using comments, formerly called cell notes.
You can view each comment when you rest the pointer over the cell or view all comments at the same time. You can print comments in the same locations where they are displayed on the worksheet or a list at the end of the worksheet.
Microsoft Excel uses the user's name in each comment.

Select cell B12.

Choose Comment from the Insert menu.

The following Cell Comment box should appear:

Within the Text Note box, type in the text: Average of nine grades and then click anywhere outside the box.

Note that there is a red note indicator in the upper- right corner of the cell. Anytime you put the mouse over the red note indicator, your comment will appear.

Now that you know how to compute the average using operators, it is time to learn how to write a formula using Excel's functions.

## Functions

Functions are used to form all or part of a formula. Excel provides two general types of mathematical functions: those that are used in business applications and those that are oriented to higher mathematics. In this tutorial we will focus on the business applications formulas.

The AutoSum button () located in the Standard toolbar.

Whenever you click the AutoSum button, Excel inserts a SUM() function in the active cell. Not only will the SUM() function write the sum formula, but it will make a guess at what range of cells you desire to sum, and will leave you in edit mode so that you can correct the sum range.

Select cell C11 and click on the AutoSum button located in the Standard toolbar.

Your worksheet should look as follows:

Excel has guessed that you want to insert cell B11, which contains the appropriate formula. Let's assume Excel did not guess correctly.

Within the formula bar highlight B11 and delete it.

The Sum function is waiting for it's arguments.

You want to sum up B2 through B10, this is denoted in a more compact form as B2:B10.

Position your cursor in the formula bar, cut out B11 and instead type in B2:B10.

Observe:

Click on the Enter button or press the Return key to enter the formula.

The Sum function is one of the many functions Excel provides. Excel also provides many statistical functions in particular the Average function.

Excel provides two ways for entering function names. You can type the name of the function in if you know it or you can use the Function Wizard.