Here, we will look at formula theory and the order of operations sothat you have a good understanding of how calculations are constructedwithin Excel 2019.

When you enter a formula into a cell, it always starts with an `=` sign is typedinto a cell on a worksheet, the Formula Bar will become active, with theformula icons changing color and becoming ready for input.

The Formula Bar is located just above the worksheet column headersand consists of three parts. To the left of the Formula Bar, you willsee a list of commonly used functions and access to the

The middle section of the Formula Bar is where you will find the iconto cancel formula input, to enter a formula, and to access the InsertFunction dialog box to search for more functions. The main part of theFormula Bar is the formula entry area where you will enter, copy, oredit calculations created in Excel. It can be expanded or collapsed,which is really useful when dealing with lengthy calculations consistingof multiple functions and operators, and can be seen in the followingscreenshot:

A formula is a cell entry that performs a calculation and returns aresult. To enter a formula, we use cell references and seldom enter acalculation, as we would do on a calculator. This is because the powerof performing calculations using references is that the data within thecell reference is often altered by the user, which in turn updates thecalculation and produces different results, depending on data input andworkflow.

In the following example, the formula is using the addition operator(+) to sum the

After entering the `=` sign, you would then select the cellreference on the worksheet for the first sales rep by clicking on cellC8, followed by the `+` operator, then the second sales repcell reference C9, and so on. Once all cell references are selected, theformula is entered into the cell by pressing the *Enter* key onthe keyboard or the green tick on the Formula Bar. To follow anyexamples in this topic, please use the `SSGRegions.xlsx`workbook. Refer to the following screenshot to view the formula inaction:

*Enter*using the keyboard key or to click on the

*green tick*on theFormula Bar to indicate you are finished constructing the formula andwould like to view the result.

In the preceding screenshot, you will see that Excel usescolor-coding to help you manage your cell references. Just at a glance,you can see which cells are matched with the cell references in theformula.

The following screenshot shows some examples of basic formulaconstruction using operators:

The operators are listed as follows:

**Add**: Type`=N7+N8`and then press*Enter***Subtract**: Type`=N7–N8`and then press*Enter***Multiply**: Type`=N7*N8`and then press*Enter***Divide**: Type`= N7/N8`and then press*Enter*