9.5 x 1.1 = 10.45, or 10.66 with rounding up, however I could easily see this go 10.33 with a crew that doesn’t throw away every little bit of cut shingle.
It is possible they are going with the added shingles as ‘starter’ & if this is the case, I would ask them to go 10.66 on shingles (less however many feet of field converted to ridge cap) & ASK THEM TO PURCHASE ‘REAL’ STARTER.
I don’t like 3T’s cut back for use as starter unless I absolutely have to (i.e. ran short or something) & most crews won’t go the added step to cut it back anyhow.
Try & ask how many linear ft. of drip edge they are calling for & if this # includes the rakes or only the eaves. If it’s rakes AND eaves, then convert this # over to ‘true’ starter.
GAF / Elk starter runs 120 linear ft. per bundle.