What did Hermione score in her Muggle Studies exam?

Hermione scored 320% on her Muggle Studies exam in Harry Potter and the Prisoner of Azkaban, which is logically impossible without magic. This was because she used a Time-Turner to attend multiple classes simultaneously, effectively retaking the exam multiple times in the same time period. The 100% would be the maximum for a single attempt, and the extreme percentages highlight the magical nature of her achievement.