I can guess how you calculate that however let me note a few things about what is quoted above.
Generally there is quite a premium per drive link with rolls less than 100 feet.
Baileys (where Woodland pro comes from) sends me promotions 10 loop for $10 each every so often. They also send me $40 off on orders of $300 and more.
The definition of an odd size is variable, If one wants say Stihl 63 chain their standard loops are 44,50,55,61 where brand x is 45,52,56,62. I can talk with the guy provide him a part number and get 56 drive link loops in a bit less than a week if I want ps or wait around while he makes up a loop of pm3 no telling how many times the phone will ring. It is about $20 where it appears I can get 25 feet and some presets off ebay and make the loops after dark.
Once I have a roll or what is left of a roll stuffed into a gallon zip lock bag of course use that unless I want skip.
If I had ten loops of woodland pro chain, at least in the sizes I have used the temptation to discard early would likely be hard to resist.