Question

A pile of 10000 sheets of paper is 85cm thick. What is the thickness of 1 sheet of paper?

Answer 1

To find the thickness of one paper, you set up proportions. 10,000 sheets/85 cm=1 sheet/ x cm. Then you cross multiply and get,
85=10,000x
Then find x,
x=.0085
Or .0085 cm
Another way to find it is just to divide 85 by 10,000 from the start because you need to find the thickness of one paper, not ten thousand. 
Hope this helps. 

Answer 2

10,000 sheets of paper is 85cm.
1 sheet of paper is xcm. K?
Since it's like 1 sheet of paper + 1 sheet of paper + (until you get 10,000 sheets of paper) is 85cm, you divide 85 by 10,000 to get the thickness of 1 sheet of paper.
85/10,000 = 0.0085
Therefore, 1 sheet of paper is 0.0085cm thick. :)