Which of the following two sentences is correct?
1. How many meters in a kilometer?
2. How many meters are there in a kilometer?
1. How many meters in a kilometer?
2. How many meters are there in a kilometer?
The answer is: both are correct
To say "how many meters in a kilometer" means the same as "how many meters are there in a kilometer".
The question itself remains and is correct in both phrasings.
The essential difference is simply this:
More words are included in the sentence to get to the same answer.
Which phrase is best to use?
Saying "how many meters are there in a kilometer" is the best way to ask this question.
By using more words and articulating the question, the answer can be more easily provided.
Using the phrase in a sentence
Example 1: John, how many meters are there in a kilometer?
Example 2: Mom, how many meters in a kilometer?
Example 3: Excuse me, sir, how many meters are there in a kilometer?
Comments
1 is not an internal structure that is attributed to a grammatical sentence.
By the way, is the following answer to question (2) correct?
There are 1000 meters in a kilometer?
Or should it be:
There is 1000 meters in a kilometer
using the logic of "1000 meters is very long for a table", which treats meters as a single unit.
It should be "There are 1000 metres in one kilometer". It means 1000 times one meter
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1000 meters is very long for a table
1000 metres in this sentence is considered a distance, and not 1000 times one meter. This is why the singular.
How many meters in a kilometer [may be a diffiulct question for some Americans]. - Yes, in this structure, it's correct; not the way it was posted. By itself, it is not a queston, nor it's a statement.
There are 1000 meteres in a kilometer.