Or am I the only one who didn't know how to calculate and didn't care to at all?

By their calculations, I came out with 2:1 and that was enough to move on with life. No time!

Seriously, I didn't care to even learn how all the As, Bs, Cs and the rest were summed to arrive at final point (CGPA).

Did you know?

Interesting

There are many people like that

I think it's highest display of nonchalant attitude not to know how calculate cgpa until you graduate from school.
My school for example only past results and do not post cgpa. We were left to do the calculations on our own and that help to keep us on our toe so that we can make up for our deficiencies in the coming semester
Every student should know how to calculate cgpa