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Harry Potter: "Arithmancy looks terrible."
Hermione Granger: "Oh no, it's wonderful! It's my favourite subject!"
Harry Potter and Hermione Granger in her third year discussing Arithmancy[src]

Arithmancy was an elective subject offered from the third year on at Hogwarts School of Witchcraft and Wizardry as well as at Ilvermorny School of Witchcraft and Wizardry.[2][1] During the 1990s at least, the class was taught by Professor Septima Vector[1] in Classroom 7A, on the Hogwarts Castle's seventh floor.[3]

Little is known about the class, but the study of Arithmancy has been described as "predicting the future using numbers", with "bit of numerology" as well.[4]

Class information

Homework assignments, which included writing essays, required the consultation and/or composition of complicated number charts.[1]

Arithmancy was Hermione Granger's favourite subject at Hogwarts. She once told Harry Potter it was "wonderful" when he remarked that her challenging homework looked "terrible".[1] However, one of her roommates said that, in her opinion, it was difficult, and by far preferred Care of Magical Creatures.

Another subject, Advanced Arithmancy Studies, was taught at Hogwarts, presumably to the most intelligent and brilliant students. It may have been taught by Professor Vector also, and the Advanced Arithmancy Studies classroom was located on the first floor of the Hogwarts Turris Magnus in Hogwarts Castle.[5]

An O.W.L. in this subject was necessary to apply for a Curse-Breaker position at Gringotts.[6]

Required textbooks

Known professors


Passing Grades

Fail Grades

Known O.W.L.s

Known N.E.W.T.s

Behind the scenes


Notes and references

  1. 1.0 1.1 1.2 1.3 1.4 1.5 Harry Potter and the Prisoner of Azkaban, Chapter 12 (The Patronus)
  2. Harry Potter and the Chamber of Secrets, Chapter 14 (Cornelius Fudge)
  3. Harry Potter and the Philosopher's Stone (video game) (Console versions)
  4. 2005 Royal Albert Hall interview with J. K. Rowling
  5. Harry Potter and the Prisoner of Azkaban (film)
  6. Harry Potter and the Order of the Phoenix, Chapter 29 (Careers Advice)
  7. Harry Potter: Hogwarts Mystery, Year 6, Chapter 7 (Niffler Hunting) - Ben mentions desiring to be a Curse-Breaker, a career which requires a O.W.L. in Arithmancy. When Ben asks Jacob's sibling if he should become a Curse-Breaker, if the player chooses the option "You should", Jacob's sibling mentions that Ben enjoys Arithmancy. As this interaction takes place in Year 6, Ben has already completed his O.W.L.s by this point and is taking N.E.W.T. level Arithmancy classes.
  8. Harry Potter and the Half-Blood Prince, Chapter 5 (An Excess of Phlegm)
  9. 9.0 9.1 Fantastic Beasts: Cases from the Wizarding World - Case 14: Fool's Gold, Act 3
  10. 10.0 10.1 Harry Potter and the Chamber of Secrets, Chapter 4 (At Flourish and Blotts) - It is said that both Percy and Bill Weasley earned twelve Ordinary Wizarding Levels, meaning they must have earned an O.W.L. in this subject.
Professors: Septima Vector
Known Arithmancers: Sage Bragnam · Lukas Karuzos · Chiara Lobosca's father · Bridget Wenlock
Textbooks: Numerology and Grammatica · New Theory of Numerology
Arithmancy at Hogwarts: Arithmancy (class) · Classroom 7A · Advanced Arithmancy Studies
Hogwarts subjects
Core classes Astronomy · Charms · Defence Against the Dark Arts · Herbology · History of Magic · Potions · Transfiguration
Elective classes Alchemy · Arithmancy · Care of Magical Creatures · Divination · Muggle Studies · Study of Ancient Runes
Extracurricular classes Apparition · Advanced Arithmancy Studies · Ancient Studies · Art · Flying · Ghoul Studies · Magical Theory · Muggle Art · Muggle Music · Music · Xylomancy
First year exams · Second year exams · Third year exams · Fourth year exams ·
Ordinary Wizarding Level · Nastily Exhausting Wizarding Test
Ilvermorny School of Witchcraft and Wizardry
Ilvermorny Houses
Horned Serpent ClearBG 2.png
Wampus ClearBG 2.png
Thundebird ClearBG 2.png
Pukwudgie ClearBG 2.png
Namesake Founders
Isolt Sayre · Chadwick Boot · Webster Boot · James Steward
Subjects offered
Arithmancy · Charms · Creature Care · Defence Against the Dark Arts · Potions · Study of Ancient Runes · Transfiguration · Xylomancy
Ilvermorny staff
William · Rionach Steward · Eulalie Hicks · Agilbert Fontaine