Answer: 1,000
Step-by-step explanation:
The height of 10 stacks of books would be a 1,000 because if it's 0.3 thick between covers of 200 sheets then 10 books would be a 1,000.
We want to find one-half of the reciprocal of 7/sqrt(98). Let's write down an expression for this:

We can rewrite 98 into 


The square root of 49 is 7



This should be your answer. Let me know if you need any clarifications, thanks!
Answer:
First let's define what modular arithmetic is, what would come is an arithmetic system for equivalence classes of whole numbers called congruence classes.
Now, the modular division is the division in modular arithmetic.
Answering the question, a modular division problem like ordinary arithmetic is not used, division by 0 is undefined. For example, 6/0 is not allowed. In modular arithmetic, not only 6/0 is not allowed, but 6/12 under module 6 is also not allowed. The reason is that 12 is congruent with 0 when the module is 6.