"We have one hundred books in our office."
I don't think 里 should be necessary - Chinese seems to function without prepositions a decent portion of the time, and this is an example when I think the "in" would be optional to translate.
It's so inconsistent with the definition of "office". Is it 办公室里 or 办公室? When you add 里, sometimes it is accepted, and sometimes not, even though the sentence asks for "office" for both.
It's because 办公室 means "office" and 里 is the preposition "in" or "inside"
I don't know, but I think it's a good question. BTW, you and I seem to think along the same lines fairly often.
The English translation of the given Chinese would seem to be: “There are 100 books in our office”. Translating from the English into Chinese I tried: “我们有一百本书在我们的办公室里”。No dice.