I'm confused with the placement of 'or not' with 'whether' in a sentence. E.g.
- I'm not sure whether I should go or not.
- I'm not sure whether or not I should go.
- Whether you stay or not, you will be charged.
- Whether or not you stay, you will be charged.
Can someone please advise which one is correct? If both are correct, is there certain situation where to use one or the other?