Of course it depends on several situation, but during an exams people are under stress and mistakes happens. What changes is the attitude of whoever is grading

Of course it depends on several situation, but during an exams people are under stress and mistakes happens. What changes is the attitude of whoever is grading them. I know one of my professor wouldn't give me full marks, but if the reasoning behind the computation was correct I would still get something. On such cases I simply wrote a note next to result saying that I understood that the results doesn't make sense and that there must be some computational mistake around but I didn't had the time to find it. Other professors wouldn't accept nothing short that the correct answer, in such cases I know that whatever note I would leave would be pointless.