I was always told by my teachers the main reason was for practicing taking exams. If you can show the workings, but you made a simple mistake somewhere, you cou

I was always told by my teachers the main reason was for practicing taking exams. If you can show the workings, but you made a simple mistake somewhere, you could still be awarded points for getting the process correct, even if the final answer is wrong. Say a trigonometry question that was worth three marks, and you messed up a decimal, you could still get one or two marks for correctly identifying the problem and solving it – albeit with the wrong number.