Depends on the sheet thickness. A general rule of thumb is 900mm total bundle height. So 900-200mm for packaging for 9mm sheets would equal roughly 77 sheets.
Ask the supplier, as quantities vary, especially if on offer.
Same answer as how many clowns fit in a clown car
A bundle of paper is called a ream. It has 500 sheets of paper.
The is no specific collective noun for sheets; a general collective can be used to suit the context of the sentence, such as a stack of sheets, a package of sheets, a box of sheets, etc.
The standard collective noun for sheets is a pad of sheets, which refers to sheets of paper. There is no specific collective noun for sheets used for bedding, in which case a noun suitable for the situation is used; for example a stack of sheets or a bundle of sheets.
Two A4 sheets make 1 A3 sheet
4 A3 sheets make up 1 A2
214 sheets of copper