@ Allie; Lol'd at your reaction. Ok, first I thought I read 1 +7 part...and also my math went like this:
3 Coupon= one +6 part------<(x3)
9 Coupon= one +6 SET------<(x3)
27 Coupon= one +7 part----->(x3)
Total=81 Coupon= one +7 SET----->(=)
So..[81x6.5]= 526.5m gigas. for a +7 set.
You said nine +5 parts, but we're really counting the combination coupon here, so 9/3=3 (3combination coupon to add a plus)