I sometimes ask a question which is a problem that I can't solve because I have made a calculative error. Often, all it takes is for someone to point out the small error I have made (or for me to realise the error after reading the answers). How should I let the users know that I have found the source of my troubles? Should it be a comment on the question, or an edit inside the body of the question? One could also answer the question, but that is probably the worst option because it takes the credit away from other users. A comment may be overlooked, so I am leaning towards putting an edit into the question. Is this standard protocol?
As an example, I have found out the reason why I have calculated the order of $\tau\sigma$ and $\tau\sigma^2$ incorrectly (by assuming commutativity) in this question.