Changing the number format from Date to Fraction doesn't work if the cell already contains a date. You must make the formatting changes before you add the values.

If the Excel cell format is not changing to a number because the Number formatting is not working, take these steps to fix the issue.

Isolate a specific value, such as a number value in cells that contain both numbers and letters by using the Excel MID function. Click in the cell where you will display the value you want to isolate.