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“Arithmancy” is their name for math classes and is mentioned several times throughout the books. It is one of Hermione’s favorite subjects.
At one point, the real world evil witch that is JK Rowling suggested that Arithmancy is like dviniation, but with math, saying they use numbers to predict the future. I take this to mean that the wizarding community discovered calculus independently from the rest of the world and mistook it for a new form of magic.
A lot of cheap kitchen scales are also just crap. Talk to your local drug dealer about what brand of scale might be right for you.