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 always wondered the opposite of the harry potter universe.
So much of math was difficult to teach or obscure because of difficulties in visualization or computation. Surely there would have been at least one wizard over hundreds of years that could figure out how to use the powers of illusion magic to visualize things? To demonstrate integrals to the unfamiliar? To render a fractal like a julia set?
Even if magic iteslf followed little internal logic, it could be used as a tool, surely? But that’s the sort of fridge logic (warning tv tropes link) that maybe didn’t belong in a story book like Harry Potter. I had to stop reading anyway around the time house elves were introduced, anyway. I took issue with that stuff even when I was a kid.