Expense Report Saved Search: Add Values of Two Columns where One Column is Blank

To do this:
1) Edit or create a search by  navigating  to Lists > Search Saved Searches.
2) Under the Results tab > Columns subtab, add Formula (Currency).
3) In the Formula box, enter this formula:
        NVL({field id 1},0)+ NVL({field id 2},0)

*Field IDs can be found on the Field Level help window when you click the Field label. This is also found when you customize the form and click Screen Fields tab. If the column is customized, navigate to Setup > Customization > Transaction Body/Column Fields > ID column.

4) Provide a name for this column in the Custom Label box (ex. Total Amount).
5) Click  Save and Run.

*** Note: NVL function forces the value to be set to the second parameter when the field id Null.