Calculate the number of days difference between two date columns

1. Make two date columns, one called Date1 and the other called Date2.
2. Make a third column (e.g. DateCalc) to calculate the difference and ensure the column type is set to Calculated.
3. In the Formula box type =DATEDIF(Date1,Date2,"D")
4. In the The data that is returned from this formula is section, click the Number radio button.