Yes I am sure 24 sheets 1 quire, but I think it is a misprint,
I may give there help line a call in the morning if someone here does
not come up with another answer.
1.a set of 24 or 25 sheets of paper; a twentieth of a ream
2.
a.four sheets of paper folded once to form a section of 16 page
b.a section or gathering
3. a set of all the sheets in a book