Modifying the Error Checking Settings

The Error Checking tab of the Options dialog box (Tools → Options), contains a list of check-box options that correspond to conditions in which Excel adds an error indicator to a cell. Note that in this list, only the first check box option has to do with actual error values in the cells. All the other options have to do with conditions that might be problematic to the spreadsheet even though they don't result in blatant error values.

Here is the entire list of Error Checking options:

Evaluates to Error Value:
Adds error indicators to cells whose formulas return error values and includes ToolTips that try to explain the reason for the particular error value.

Text Date with 2 Digit Years:
Adds an error indicator to cells that contain two-digit dates entered as text, as in '89 or '76.

Number Stored as Text:
Adds an error indicator to cells that contain numbers entered as text, as in '1123 or '45.67.

Inconsistent Formula in Region:
Adds an error indicator to any cells containing formulas whose structures don't match the prevailing pattern in the rest of those in a particular table.

Formula Omits Cells in Region:
Adds an error indicator to any cells containing formulas that don't refer to cells within a particular table when most of the others do.

Unlocked Cells Containing Formulas:
Adds an error indicator to any unlocked cells containing formulas (you can unlock cells by pressing Ctrl+1, clicking the Protection tab, and deselecting the Locked check box).

Formulas Referring to Empty Cells:
Adds an error indicator to any cells containing formulas referring to empty cells. (This is the only Error Checking option not selected by default.)

List Data Validation Error:
Adds an error indicator to cells that contains entries that don't follow the data validation condition applied to them.

As you can see from the list of Error Checking options, error indicators often don't represent an error per se but simply an anomaly in the prevailing pattern. If you're not particularly concerned about inconsistencies in your spreadsheets, you can simply deselect their check box options to prevent Excel from cluttering the worksheet with these types of indicators.

Don't disable the Evaluates to Error Value option unless you're a real spreadsheet ace who can immediately tell what's causing a formula to return an error value. You'll be cheating yourself out of the ToolTip info telling you what's wrong so you can quickly eliminate the error.

You can make the error indicators more or less prominent in the worksheet by selecting a new color for their triangles on the Error Indicator Color pop-up palette.