## Writing Formulas Using Operators and Functions

Operators are what connects the elements of a formula. Some familiar operators are: addition (+), subtraction (-), multiplication (*), and division (/). There is an order of operations when you are evaluating a formula. Formulas are evaluated from left to right, with expressions enclosed in parentheses evaluated first, then exponents, multiplication, division, addition, and subtraction. Excel has many more operators, but we will work with the operators listed above for now.

Here is an example of how the order of operations works:
If you have the following formula within a cell;
=A8/(A9+A4)

The first operation would be the sum of A9 and A4 and then A8 would be divided by that sum.

Describing Formulas
Excel allows you to add comments to explain the purpose of an inserted formula. The comments are displayed in the Cell Note window which can be viewed by choosing Note from the Insert menu. Let's enter a formula using operators and comment the formula.

Open a new workbook window.

Starting in cell A1 build the following table:

You are going to enter a formula which will calculate the average of these nine grades.

Select cell A11 and type in the text:Total.

It would be best if the total sum of the grades was beneath the last grade. You need to insert a column between column A and column B so you don't have to retype all the numbers.

## Insert a Column

Highlight column A by clicking in the column heading.

Observe:

Choose Columns from the Insert menu.

Column A should be a blank column now.

Select cell B1 and click in the formula bar.

Highlight the text:Grades and Cut and Paste the text into cell A1.

Cut and Paste the text:Total into cell A11.

Now to enter the formula for the total sum of the grades.

Select cell B11 and enter the following formula:
Remeber to click on the Enter button or press the Return key to enter the formula.

Your worksheet should look as follows:

Select cell A12 and enter the text:Average.

Select cell B12 and enter the following formula:

Your worksheet should look as follows:

Let's annotate (comment) the formula in cell B12.