Recently someone asked a question about an argument in a textbook which (s)he did not understand.
Some people quickly noticed that the confusion was just caused by a typographical error in the book, and posted that as comments.
But (apart from not recognizing the typo) it was a good question: OP tried to follow the argument from the book and showed the calculations until (s)he got stuck.
- My question is: Is such a question on-topic, or should it be closed?
If it is on-topic, would “that is a typo, X should be Y” be a valid answer if there is nothing else to say? That would be helpful to the author of the question, but probably not to many future reader of the thread.
If it is off-topic, what should be the closing reason? “Unclear what you're asking” does not really fit the situation.