6 means 90-96%. Here we discuss the transfer for grade 12 students because it would impact university application. Actually Mark 7 in IB does not mean you get 97% and up in the exam, it is a relative mark. For example if there were 100 points, you got 78, your mark would still be 7 if you were on the top. During the school year, IB student have lots of exams,tests from their teacher, the teacher will mark their test according to IB standard. Probably the student could not get 90%, but the mark the student got would be rank 7 in the IB exam per the teacher's experience. so the teach would transfer the lower mark to high mark. I hope my explanation is clear enough. I don't know if you can read Chinese, if you can, it is better type Chinese here.