First let me stress that for the first mentioned question, I now reopened the question. In that sense I agree that the current version seems like an alright question to me. I strongly suspect it is a duplicate, but that is a somewhat though not entirely separate concern.
This out of the way let me try to explain why this post, and such posts more generally, can get closed.
A point to note is that the first version of the post read like this:
Why 1/0.5 equal 2?
I would like to know 1/0.5 =2 is why the 1/0.5 gets 2. I want to know the concept not how to get the answer. If you are able to explain this in example using image that would be super helpful!
It's hard to know where to start here. The question is in a way too broad, or it lacks details and context.
The questioner then rectified this a bit by adding:
My understand is if you divide whole pizza we get 2 halves slice of pizzas which is 1/2. So, 1/0.5 = 2 mean you will get 2 whole pizza?
I would say with this addition one has at least a relatively good idea where the questioner is standing in their understanding of the subject. Thus, one might try to answer.
However, when this addition was made the post already had a vote to close and was in the close queue. It then can be an uphill battle. The question was alright, yet not great either, and also towards the simple and well-known end. Thus, many a user will vote to close it in the queue.
The other thing is that I assume many will assume, and rightly so, that certainly this got asked already, which might influence the decision. But, in that case one likely should provide at least some link. Then again, there were answers already anyway, so one might think what's the point of me spending five minutes to search for links, the questioner anyway got an answer.
An issue is that as mentioned in a comment the volume is pretty high and some users that moderate a lot might keep it short at times.
All that said, given that it was a new user and they in the end made some effort, arguably the reception is a bit harsh. However, they also got answers and no one was snide or anything. In that sense, I would not consider it as an example of the site being toxic either.