all my dates suddenly appear as the underlying number

Copper Contributor

I have built and used this spreadsheet for years.

Suddenly one day all the dates now appear as the underlying number instead of the normal date MM/DD/YYYY


Even when format such a cell as a date it ignores this and the number still appears.


This applies to old cells and new cells input as a date.



2 Replies


automatically changing numbers


  • If a number is left-aligned in a cell that usually means it isn’t formatted as a number.

  • Depending on the number entered, you may see a small green triangle in the upper left corner of the cell, indicating that a number is stored as text, which to Excel is an error. Either ignore the triangle, or click on it. A box will appear to the left. Click the box, and then select Ignore Error, which will make the triangle go away.


Activate the Formulas tab of the ribbon.

Make sure that the 'Show Formulas' button in the 'Formula Auditing' group is not highlighted.