so does the fetus technically not have a skeleton before then?

The cartilaginous pre-bones would still be a skeleton. Sharks have skeletons, but don’t have any bones for example.

Will no one bring down the average? I guess they won’t be stepping up …

Everyone else is failing to count the number of babies (140 million per year) nearly all of whom have 100% complete skeletons and set that against the number of amputations of perhaps a few percentage points across a much smaller number of people annually (“more than 1 million annually”).

I’d argue teeth aren’t skeleton because they’re not made of the same substance as bone - the outside is enamel and dentin whereas bones are collagen, protein and minerals (mostly calcium). Kinda like how hair and nails don’t count because they’re made of keratin.

I’d argue you still have one skeleton if you lose limbs or teeth.

Amount of skeletons is an integer representing the anount of bone structures holding and protecting human body (or whatever’s left of it).

The real question is, how much of which parts of skeleton can we lose with it still being skeleton instead of a set of bones?

For the sake of this exercise we’ll consider skeletons rounded to whole integers. And air resistance may be ignored.