Badly stored data alert...
This is a typical problem associated with a spreadsheet style storage method. As you have now discovered it doesn't scale well and makes doing apparently easy things very difficult.
You'll have to literally add them up manually - PainfullResult: Field1 + Field2 + Field3 etc etc.
When you add column 9 you'll have to hardcode that back into your query, and if you have null values anywhere you have to encompass them to continue the sums to work.