"Arithmancy looks terrible," said Harry, picking up a very
complicated-looking number chart.
"Oh no, it's wonderful!" said Hermione earnestly. "It's my favorite
Arithmancy class is taught at Hogwarts by Professor Vector.
- In Professor Vector's class, students are expected to write essays and to be able to understand complicated number charts, which are part of their homework (PA12).
- Hermione Granger appears to be the only Gryffindor in her year who attempted an O.W.L. in this subject (which is her favourite) (PA12, PA16).