[Request] How many pieces of A4 paper can be made from a single tree?

Just curious as one of my lecturers was teaching a lecture on sustainability. She printed out a two page handout. For all 1000 students. Oh the irony.

So my question is how many pieces of A4 paper can be made from a single tree and how many trees, or what percentage of a tree, did my lecturer destroy?

EDIT: HowStuffWorks seems to estimate 80,500 sheets.