You can use error checking to detect errors in formulas. The rules don't guarantee error-free worksheets, but they can help find common mistakes. Errors can include: Cells containing formulas that result in an error, inconsistent calculated column formula in tables, cells containing years represented as 2 digits, numbers formatted as text or preceded by an apostrophe, formulas inconsistent with other formulas in the region, formulas which omit cells in a region, unlocked cells containing form...