If numbers keep changing to dates automatically in Excel or if Excel changes dates to random numbers then this post will help you fix the issue. As reported by some users, whenever they enter a number ...

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.

When you see the #VALUE error, it means that there is something wrong with the way the formula is typed, or there is something wrong with the cells you are referencing.