I changed my mind.
Replace a number you no longer believe, without losing the one you did.
What to do
- File the new number on the same question. It supersedes the old one; you do not delete anything.
- Say what changed. A revision carries a dated explanation, and this is required rather than encouraged — the explanation is the part that will still be useful to you in six months.
- Both numbers stay on your record, in order, with their dates. That is deliberate: a record that hid the earlier view would make revising look like an admission.
If that does not work
If the question has closed, the number stands as your last word on it. A closed question accepts no further judgment, including a better one.
Still stuck? The other tasks may cover it. If what you actually want is to judge better rather than to finish this, that is the Learning Centre.