Prime Numbers

Despite being a self-confessed math-phobic J.K. Rowling has certainly had some fun with numbers in the Harry Potter universe. In a previous episode we talked about wizard currency being built on prime numbers, with 29 knuts to a sickle and 17 sickles to a galleon. Prime numbers crop up elsewhere in the series too. The most obvious is the number seven, described as the most powerfully magical number of all. Seven books, seven years, seven Horcruxes, seven Weasley children, Harry’s wand cost seven galleons, and many more examples. Thirteen also features, most notably when Professor Trelawney describes the ill omen of having thirteen dine together for Christmas dinner in Prisoner of Azkaban. Put 7 and 13 together and you have the number of the vault in Gringotts from which Hagrid retrieved the Philosopher’s Stone. Seven and thirteen were also the directions Dumbledore gave to Harry and Hermione for rescuing Sirius and Buckbeak – 7th floor, 13th window.

Three is another prime number which features extensively – the trio of Harry, Ron and Hermione, three Hallows, three types of wand core, three Unforgivable Curses.

Students receive their Hogwarts letter on their eleventh birthday, and the Hogwarts Express leaves at 11 o’clock – another prime number.

Wizards come of age on their 17th birthday, and the Epilogue is set 19 years later – yet more prime numbers.

Could this preponderance of prime numbers be a coincidence? I doubt it.



In the Harry Potter Lexicon Minute podcast you’ll hear the voices of our editors sharing some of the many little things which delight us about the Wizarding World. In each podcast, one to two minutes in length, we’ll talk about anything from cool trivia and interesting canon passages to the latest Wizarding World news. We hope you’ll join us! And we’d love to hear from you as well. Feel free to use the comment section on the blogpost for each podcast to post your thoughts.

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