"If being good at Divination means I have to pretend to see death omens in a lump of tea leaves, I'm not sure I'll be studying it much longer! That lesson was absolute rubbish compared with my Arithmancy class!"
—Hermione Granger's opinion of the class[src]

Arithmancy is a magical discipline that studies the magical properties of numbers, including predicting the future with numbers and numerology.[1] Those who practised Arithmancy were called Arithmancers.

Arithmancy was an elective subject offered from the third year on at Hogwarts School of Witchcraft and Wizardry, the homework assignments of which included writing essays that required the consultation and/or composition of complex number charts.[2]


Numerology and Grammatica,[3] a third year textbook at Hogwarts.

New Theory of Numerology, which Harry Potter gave to Hermione Granger for Christmas in 1995.[4]

Notable Arithmancers

Wizard(s) Notes
Bridget Wenlock the archetypal example; she was a celebrated witch who first discovered the magical properties of the number seven in the 13th century.[5]
Septima Vector taught Arithmancy and Advanced Arithmancy Studies at Hogwarts School of Witchcraft and Wizardry for at least six years (possibly more).
Hermione Granger famous high-ranking official in the Department of Magical Law Enforcement, who strongly contributed to Voldemort's downfall as she accompanied Harry Potter in the hunt for horcruxes; translated the Tales of Beedle the Bard into English from Runic.
Percy Weasley Achieved an O.W.L. in this subject
William Weasley Achieved an O.W.L. in this subject and works as a Curse-Breaker for Gringotts
Bartemius Crouch Jr Death Eater who made Lord Voldemort's second rising possible.
Curse-Breakers most likely, as an O.W.L. in Arithmancy is required to take the job.

Arithmantic texts


Arithmancer and Arithmancy come from the Greek αριθμός (arithmos), meaning "number", and μαντεία (manteia), meaning "divination". Hence "Arithmancy" literally means "number divination", which is fitting.

Behind the scenes

  • In reality, the term "Arithmancy" refers to a supposed form of divination based on assigning numerical values to words or phrases; the term "Numerology", referred to in canon as a branch of Arithmancy, refers to any of a number of different beliefs in a divine or mystical relationship between a number and coinciding events.
  • Hermione has expressed open contempt for the subject of Divination, yet has also proclaimed that Arithmancy (in which numerology is prominent) is her favourite subject. While this may seem contradictory at first, a possible explanation is that Arithmancy applies a more rigorous and mathematical approaches to predicting the future (which the scientifically-inclined Hermione would respond to), unlike Divination, which she detested because it seemed to be "a lot of guesswork."
  • Some fans[citation needed] have speculated that the field of Arithmancy, within the universe of Harry Potter, serves as a foil to the wooliness of Divination in that it might be a magical equivalent to probability calculations. If this is indeed the case, this might explain why the subject would be required for Curse-Breakers (it would allow them to evaluate the potential success of a curse-breaking strategy without having to actually do it, meaning they could minimise the risk of failure and/or injury).


Notes and references

External links

Professors: Septima Vector
Known Arithmancers: Bridget Wenlock
Textbooks: Numerology and Grammatica · New Theory of Numerology
Arithmancy at Hogwarts: Arithmancy (class) · Classroom 7A · Advanced Arithmancy Studies