Closing a “not a real question” that *could* make sense

Edit: This is not a proposal. I am just asking what I should be doing.

In this question: Number theory - Primitive root of $338$ the question as stated doesn't make any sense. However, in the comments a user has explained what the OP (probably) means. I sometimes see these questions where the question as stated doesn't make sense, but I (or someone else) can make a good guess as to what the OP really wants to know.

Is it better to just close the question, or should one just edit the question so that it makes sense (with the risk of changing the questions so that it actually isn't what the OP wants to know)?

Obviously, if the OP clarifies in the comments what the question really is, one can make the edit, but what about when the OP remains silent?

• Sorry, I didn't mean to get specific about this one question. I was trying to be more general. – Thomas Mar 31 '13 at 12:54