The problem with modifying formula variables is that you see only a single result at one time. If you're interested in studying the effect a range of values has on the formula, you need to set up a data table. In the investment analysis worksheet, for example, suppose that you want to see the future value of the investment with the annual deposit varying between $7,000 and $13,000. You could just enter these values in a row or column and then create the appropriate formulas. Setting up a data table, however, is much easier, as the following procedure shows:
1.  Add to the worksheet the values you want to input into the formula. You have two choices for the placement of these values:

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4.  How you fill in this dialog box depends on how you set up your data table:

5.  Click OK. Excel places each of the input values in the input cell; Excel then displays the results in the data table, as shown in Figure 14.4. Figure 14.4. Excel substitutes each input value into the input cell and displays the results in the data table. 