Number Stored As Text

This rule will identify cells that contain numbers that have been formatted as text or have been preceded by an apostrophe.

Smart Tag Menu

Convert to Number - Changes the number format to "General" so it will be stored and displayed as a number.
Help on this Error - Displays the Help task pane.
Ignore Error - This removes the green triangle from the cell and the cell is no longer considered an error.
Edit in Formula Bar - Places the cursor into the Formula bar so it can be edited.
Error Checking Options - Displays the Options, Formulas Tab.

Example

When a cell that has been formatted as Text, contains a Number.
Enter the number 20 into cell "B2".

Right mouse click and select "Format Cells".
Display the Number tab and change the category to "Text".

Any cells formatted as text are left aligned by default.
Change the value of the number. Enter the number 30 into cell "B2".