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calculation. This is often helpful in locating problems that prevent the for- mula from returning the hoped for or expected results.
To evaluate a formula step-by-step, position the cell pointer in that cell and then click the Evaluate Formula command button on the Formulas tab (or press Alt+MV). This action opens the Evaluate Formula dialog box with an Evaluation list box that displays the contents of the entire formula that’s in the current cell.
To have Excel evaluate the first expression or term in the formula (shown underlined in the Evaluation list box) and replace it with the currently calcu- lated value, click the Evaluate button. If this expression uses an argument or term that is itself a result of another calculation, you can display its expression or formula by clicking the Step In button (see Figure 2-10) and then calculate its result by clicking the Evaluate button. After that, you can return to the evaluation of the expression in the original formula by clicking the Step Out button.
Figure 2-10:
Calculating each part of a formula in the Evaluate Formula dialog box.
Formula Auditing 359
After you evaluate the first expression in the formula, Excel underlines the next expression or term in the formula (by using the natural order of prece- dence and a strict left-to-right order unless you have used parentheses to override this order), which you can then replace with its calculated value by clicking the Evaluate button. When you finish evaluating all the expres- sions and terms of the current formula, you can close the Evaluate Formula window by clicking its Close button in the upper-right corner of the window.
Instead of the Evaluate Formula dialog box, open the Watch Window dialog box by clicking the Watch Window button on the Formulas tab (Alt+MW) and add formulas to it when all you need to do is to keep an eye on the current value returned by a mixture of related formulas in the workbook. This enables you to see the effect that changing various input values has on their calcula- tions (even when they’re located on different sheets of the workbook).
Book III Chapter 2
Logical Functions and Error Trapping