Convert Blank Grades to Zeroes

"Perform bulk insert" to fill in blanks with "0:"

 1)      Click the "Grades" tab;

2)      In the drop down menu choose "Single view;"

3)      Click "Grade items," then In the "Select grade item" drop down, click the item you want to do the bulk action;

4)      In the "Actions" menu, click  the "Perform bulk action" 

5)      Click the "Empty grades" radio button

5)      Once you are set, click "Save."