The uniform mark score (UMS) which is out of 100 per module is 40 for an E, 50 D, 60 C, 70 B and 80 A but the actual paper is out of 75. The average of the 3 module scores will give you the AS grade. To complicate things, the conversion to UMS scores is not as straightforward as converting to a percentage and the raw score boundaries will vary from module to module and from year to year. Last Summer the raw scores needed were as follows :- Core 1 60 A 52 B 44 C 37 D 30 E Core 2 67 59 51 43 36 and then there would also be a 3rd module such as Stats, Mechanics or Decision Maths which each had different boundaries too. Know its complicated but hope it gives you some idea.