He was abducted by Hagrid when he turned 11 so that would place him maybe around the fifth or sixth grade.
I don’t know if canonically there are math classes at Hogwarts.
The thought came to while I was watching the anime Mashle. If you are into Harry Potter and One-Punch Man I’d recommend giving it a watch.
Someone mentioned this community below; I wanted to highlight it.
Small promotion for !harrypotter@literature.cafe
I think you’re right. They probably don’t know math. I mean, what would they need it for? They probably don’t have to follow the laws of physics for the most part. If math is done it’s probably 100% recreational.
Around that age kids learn what negative numbers are. I feel like some of it might be important