it always helps if you can upload the spreadsheet itself. Descriptions go only so far...
Without seeing it, one thought I have--a variation on something I'll do occasionally with Pivot Tables--is to just create in the underlying data source for that Pivot Table, a "helper column" that contains the exact number you're looking for as the basis for that axis of the final table. It's sometimes just easier to do it in the data source than in the "field settings" of the Pivot Table itself.