Chapter 8: Playing with Formulas 161 2. Type the equal sign (=). This tells Excel that you are creating a formula. 3. Type your formula that includes one or more cell references that identify cells that contain data, such as A4 or E8. For example, if you want to add the numbers stored in cells A4 and E8, you would type =A4+E8. 4. Press Enter. Typing cell references can get cumbersome because you have to match the row and column headings of a cell correctly. As a faster alternative, you can use the mouse to click any cell that contains data; then Excel types that cell reference into your formula automatically. To use the mouse to click cell references when creating a formula, follow these steps: 1. Click in the cell where you want to store the formula. (You can also select the cell by pressing the arrow keys.) Excel highlights your selected cell. 2. Type the equal sign (=). This tells Excel that anything you type after the equal sign is part of your formula. 3. Type any mathematical operators and click any cells that contain data, such as A4 or E8. If you want to create the formula =A4+E8, you would do the following: a. Type =. This tells Excel that you’re creating a formula. b. Click cell A4. Excel types the A4 cell reference in your formula automatically. c. Type +. d. Click cell E8. 4. Press Enter. Excel types in the E8 cell reference in your formula automatically. After you finish creating a formula, you can type data into the cell references used in your formula to calculate a new result.
162 Part III: Playing the Numbers with Excel Organizing formulas with parentheses Formulas can be as simple as a single mathematical operator such as =D3*E4. However, you can also use multiple mathematical operators, such as =A4+A5*C7/F4+D9 There are two problems with using multiple mathematical operators. First, they make a formula harder to read and understand. Second, Excel calculates mathematical operators from left to right, based on precedence, which means a formula may calculate results differently than you intended. Precedence tells Excel which mathematical operators to calculate first, as listed in Table 8-2. For example, Excel calculates multiplication before it calculates addition. If you had a formula like =A3+A4*B4+B5 Excel first multiplies A4*B4 and then adds this result to A3 and B5. Table 8-2 Mathematical Operator Operator Precedence in Excel Description : (colon) Reference operators (single space) , (comma) – Negation % Percent ^ Exponentiation * / Multiplication and division + – Addition and subtraction & Text concatenation = < > = Comparison Typing parentheses around cell references and mathematical operators not only organizes your formulas but also tells Excel specifically how you want to calculate a formula. In the example =A3+A4*B4+B5, Excel multiplies A4 and B4 first. If you want Excel to first add A3 and A4, then add B4 and B5, and finally multiply the two results together, you have to use parentheses, like this: =(A3+A4)*(B4+B5)