Arithmancer

An Arithmancer is a wizard or witch who practises Arithmancy, a specific branch of magic that involves the complicated and magical properties of numbers. The primary application of Arithmancy is a form of Divination, used to predict the future through intricate calculations and numerical charts. This discipline is presented as a more rigorous, logical, and academic form of future-telling compared to other methods such as Tessomancy (reading tea leaves) or Crystal Gazing, which are often viewed as imprecise arts. An Arithmancer relies on intellect and complex formulae rather than intuition or the 'Inner Eye'.

Arithmancy is an elective subject offered to students at Hogwarts School of Witchcraft and Wizardry from their third year onwards. It is known to be a particularly challenging course, requiring a high degree of logical reasoning and academic dedication. The class involves interpreting complicated number charts and writing essays on the findings. The subject was taught by Professor Septima Vector during Harry Potter's time at Hogwarts. Hermione Granger chose to study Arithmancy, partly because she found the vagueness of standard Divination to be frustrating. Her decision to take the class, along with every other elective, necessitated the use of a Time-Turner during her third year.

While few Arithmancers are mentioned by name, several characters are noted for their connection to the practice:

• Bridget Wenlock: A celebrated 13th-century Arithmancer who was the first to establish the magical properties of the number seven. (video game)
• Professor Septima Vector: The Arithmancy professor at Hogwarts during the 1990s.
• Hermione Granger: The most prominent student of Arithmancy in the series. She excelled at the subject and continued with it to N.E.W.T. level, finding its logical framework far preferable to Professor Sybill Trelawney's Divination class, which she ultimately dropped.

The primary function of an Arithmancer is to predict the future. However, the principles of Arithmancy have broader applications in the Wizarding World.

• Professional Careers: A proficiency in Arithmancy is considered a valuable skill for certain high-level professions. Bill Weasley noted that it would be a useful subject for someone hoping to become a Curse-Breaker for Gringotts Wizarding Bank.
• Magical Theory: The study of magically significant numbers is a core tenet of Arithmancy. The concept of seven being the most powerfully magical number, as mentioned by Professor Horace Slughorn to a young Tom Riddle in the context of creating Horcruxes, is a principle derived from this field of study.

The term “Arithmancer” is a direct derivation from “Arithmancy.” The word Arithmancy itself originates from the Greek words arithmos (ἀριθμός), meaning “number,” and manteia (μαντεία), meaning “divination.” Therefore, an Arithmancer is literally “one who performs divination by numbers.”

• Arithmancy, or Arithmomancy, is a real-world form of divination with roots in ancient Greek and Chaldean traditions, which associated numbers with divine or mystical significance.
• In the video game Hogwarts Legacy, the principles of Arithmancy are presented as a gameplay mechanic. Numerous puzzle doors are scattered throughout Hogwarts Castle, which can only be opened