https://en.wikipedia.org/wiki/Arithmancy
https://harrypotter.fandom.com/wiki/Arithmancy
https://en.wikipedia.org/wiki/Numerology
https://harrypotter.fandom.com/wiki/Numerology
https://www.pottermore.com/features/the-significance-of-seven-infographic
https://harrypotter.fandom.com/wiki/Seven
