- Introduction
- Understanding Formulas
- Creating a Simple Formula
- Creating a Formula Using Formula AutoComplete
- Editing a Formula
- Understanding Cell Referencing
- Using Absolute Cell References
- Using Mixed Cell References
- Using 3-D Cell References
- Naming Cells and Ranges
- Entering Named Cells and Ranges
- Managing Names
- Simplifying a Formula with Ranges
- Displaying Calculations with the Status Bar
- Calculating Totals with AutoSum
- Performing One Time Calculations
- Converting Formulas and Values
- Correcting Calculation Errors
- Correcting Formulas
- Auditing a Worksheet
- Locating Circular References
- Performing Calculations Using Functions
- Creating Functions
- Creating Functions Using the Library
- Calculating Multiple Results
- Using Nested Functions
- Using Constants and Functions in Names

## Understanding Formulas

### Introduction

A formula calculates values to return a result. On an Excel worksheet, you can create a formula using constant values (such as 147 or $10.00), operators (shown in the table), references, and functions. An Excel formula always begins with the equal sign (=).

A **constant** is a number or text value that is not calculated, such as the number 147, the text “Total Profits”, and the date 7/22/2010.
On the other hand, an **expression** is a value that is not a constant. Constants remain the same until you or the system change them. An **operator** performs a calculation, such as + (plus sign) or - (minus sign). A cell **reference** is a cell address that returns the value in a cell. For example, A1 (column A and row 1) returns the value in cell A1 (see
table below).

A **function** performs predefined calculations using specific values, called arguments. For example, the function SUM(B1:B10) returns the
sum of cells B1 through B10. An argument can be numbers, text, logical values such as TRUE or FALSE, arrays, error values
such as #NA, or cell references. Arguments can also be constants, formulas, or other functions, known as **nested functions**. A function starts with the equal sign (=), followed by the function name, an opening parenthesis, the arguments for the
function separated by commas, and a closing parenthesis. For example, the function, AVERAGE(A1:A10, B1:B10), returns a number
with the average for the contents of cells A1 through A10 and B1 through B10. As you type a function, a ToolTip appears with
the structure and arguments needed to complete the function. You can also use the Insert Function dialog box to help you add
a function to a formula.

### Perform Calculations

By default, every time you make a change to a value, formula, or name, Excel performs a calculation. To change the way Excel performs calculations, click the Formulas tab, click the Calculation Options button, and then click the option you want: Automatic, Automatic Except Data Tables, or Manual. To manually recalculate all open workbooks, click the Calculate Now button (or press F9). To recalculate the active worksheet, click the Calculate Sheet button (or press Shift+F9).

#### Precedence Order

Formulas perform calculations from left to right, according to a specific order for each operator. Formulas containing more than one operator follow precedence order: exponentiation, multiplication and division, and then addition and subtraction. So, in the formula 2 + 5 * 7, Excel performs multiplication first and addition next for a result of 37. Excel calculates operations within parentheses first. The result of the formula (2 + 5) * 7 is 49.