Microsoft Office

Making Your Worksheets Error-Free 32
Pay Attention to the Colors
When you edit a cell that contains a formula, Excel color-codes the cell and range references in the formula.
Excel also outlines the cells and ranges used in the formula by using corresponding colors.
Therefore, you can see at a glance the cells that are used in the formula.
You also can manipulate the colored outline to change the cell or range reference. To change the references
that are used in a formula, drag the outline’s border or fill handle (at the lower-right corner of the outline). This
technique is often easier than editing the formula.
A common problem is using a relative reference when you should use an absolute reference. As shown in
Figure 32.2, cell C1 contains a tax rate, which is used in the formulas in column C. The formula in cell C4 is
=B4+(B4*$C$1)
FIGURE 32.2
Formulas in the range C4:C6 use an absolute reference to cell C1.
Notice that the reference to cell C1 is an absolute reference. When the formula is copied to other cells in
column C, the formula continues to refer to cell C1. If the reference to cell C1 were a relative reference, the
copied formulas would return an incorrect result.
Operator precedence problems
Excel has some straightforward rules about the order in which mathematical operations are performed (see
Chapter 11). When in doubt (or when you simply need to clarify your intentions), you should use parentheses
to ensure that operations are performed in the correct order. For example, the following formula
multiplies A1 by A2 and then adds 1 to the result. The multiplication is performed first because it has a
higher order of precedence.
= 1+A1*A2
The following is a clearer version of this formula. The parentheses aren’t necessary, but in this case, the
order of operations is perfectly obvious.
=1+(A1*A2)
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