Most match extras that require a number/count for a prediction will be followed by a (+/- X). This indicates that you will get points for a correct guess within the defined range.
If you accurately predict a (+/- X) match extra, with no variance, you will earn two additional points.
A match extra has a (+/- 1) and the correct answer is 4, you will earn the base points for a prediction of 3, 4 or 5. If your prediction was exactly 4 you would also earn the bonus points.