When I was a kid, a friend of mine in a different school (a private school, where unfairness of grading was not a topic students could bring up) told me how his class had a test marked out of 150 points. To convert the score to percentage, the teacher divided scores over 100 by 2, and left the rest the same. In other words 140/150 counted as 70%, while 90/150 counted as 90%.