If a question is closed (put on hold) on MathOverflow as off-topic for not being research level-question, but it is still a question about mathematics. What might be a suitable place for such question? What should I know before asking there?
Often when a user asks a question not belonging on this site, they receive some advice in comments where and how they should ask the question, it might be a good idea to collect advice on this topic in one place, so that a link to this post can be provided in comments.