In Dutch schools, notes go from 1 to 10, including in the final exam which decides whether you pass the 'middle' school (sort of like high school I guess) and then can go on to a university, college, some other form of next education or whatever.
Anyhow, I bombed two subjects in my final year exams, maths and chemistry. You can retake one, with my options being as follows: retake chemistry and get it from a 4.x to a 5.4 or higher, or retake maths and get it from a 2.x (!) to a 4.something. This should tell you enough about my mathematical knowledge.
Circles have interesting mathematical capabilities and I'm sure triangles and rectangles do too, if one were too understand maths, which I don't. I am going for C, square root!