In modern numerological terminology, arithmancy (a shortened form of Greek u1F00u03C1u03B9u03B8u03BCu03BFu03BCu03B1u03BDu03C4u03B5u03AFu03B1 divination by numbers) is a form of divination based on assigning numerical value to a word or phrase, by means of a simplified version of ancient Greek isopsephy or Hebrew/Aramaic gematria, as adapted to the Latin alphabet...
Divination using numbers that are the equivalent of letters of a name
(arithmancer) someone who practices arithmancy
Is a branch of magic concerned with the magical properties of numbers. As neither Harry nor Ron take this class, almost nothing is known about it. It is, however, a favourite subject of Hermione. Arithmancy is reportedly difficult, as it requires memorising or working with many charts. ...
A class taken by Hermione, dealing with the study of numbers; an early form of numerology where divination is made through numbers (especially those numbers associated with the letters of a person's name)