How hard is it to rearrange your statement into a question? If it's too hard, do you leave the question mark off?
Rearranging a statement into a question form should be easy.
If you leave the question mark off, it would not be (grammatically) a question.
[I am not certain that I understand this question].
Examples of conversion of statement into questions:
(in less formal, but common usage, asking for confirmation)