To set this up, just follow these steps:
- Select C2:D17.
- Go to Format | Conditional Formatting. In Excel 2007, click Conditional Formatting on the Home tab and choose New Rule (Figure B). Then, click Use A Formula To Determine Which Cells To Format (Figure C).
- Click the Format button.
- On the Patterns tab, choose yellow, and click OK. In Excel 2007, on the Fill tab, select yellow under Background Color and click OK.
- Choose Formula Is from the Condition 1 drop-down list and enter the following formula: =COUNTIF($C$2:$D$17,C2)>1. In Excel 2007, you'll enter the formula in the Format Values Where This Rule Is True text box.
- Click OK again to return to your worksheet.
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