I would like to keep my total hours worked (sum) for the month.
Update the next month and have my (sum) not lose info but let me add to it,
the new month.
This is current formula:
=SUM(D7*3,C7*2,B7*1.5)
If I clear D7, C7, B7 - I now lose my data in SUM field.

This box (sum) is repeated several times, all dif. employees.
How do I keep a sum from losing its value? And allow it to be updated (add)
new hours to it?