microsoft excel 2010How do you add an overline to letters in Microsoft Excel 2010?

Hi, I'm wondering how you add an overline OVER a letter in Microsoft Excel 2010 for some homework. Any help would be appreciated and most helpful answer will get 10 points. Thank you!
In the Insert Symbols dialog, microsoft excel 2010there is a character called the 'Combining Overline'. It is in the 'Combining Diacritical Marks' section (after 'Spacing Modifier Letters'). You put it behind whatever character you actually want overlined.
microsoft excel 2010
It doesn't mean anything to Excel—it's just a non-number, and may turn a numerical value into a text string (that doesn't calculate in formulas!).