Seven

Seven was the most powerful magical number, based on centuries of mythology, science, and mathematics, and therefore had a very important role in the wizarding world. Arithmancer Bridget Wenlock was the first to note this through a theorem which exposed the magical properties of the number seven. 
==History==
The Arithmancer, Bridget Wenlock (1202–1285) was the first witch to establish the magical properties of the number seven. She wrote her ground-breaking theorem on the back of a sugar packet, using her usual invisible ink. She then proceeded to send her cousin a letter, forgot where she wrote the theorem, and thought it was on the envelope. She hunted down the envelope and intercepted it at her cousin's house, where she learned her mistake. 
Seven was the age by which most experts believed that magic would reveal itself in a wizard or witch.
==Seven seen in the wizarding world==
====Names====
*"Weasley" contained seven letters.
*"Granger" contained seven letters.
*The following people had seven syllables in their full names:
**Ronald Bilius Weasley
**Hermione Jean Granger
**Ginevra Molly Weasley
**William Arthur Weasley
**Percy Ignatius Weasley
**Albus Severus Potter
**Regulus Arcturus Black
**Minerva M McGonagall
*The names Lily Evans and James Potter had seven syllables altogether.
*The Arithmancy professor, of Hogwarts, was named Septima Vector. Her first name was also seven letters long.
*Septimus Malfoy and Septimus Weasley had a shared first name that translated to "seventh" in Latin.
*Marvolo, Tom Riddle's middle name, had seven letters in it.
*If the letters of the alphabet were turned into numbers (A=1, B=2, etc...), the letters in the name Harry would add up to 70. (8+1+18+18+25=70)
*If the letters of the alphabet were turned into numbers (A=1, B=2, etc...), and added together until a single number was found, as done in Arithmancy, the letters in the name Harry resulted in the number 7. (8+1+18+18+25=70, 7+0=7)
*"Bridget" and "Wenlock", the first and last names of the person who established the magical properties of seven, both contained seven letters.
====Birth====
*Molly and Arthur Weasley had seven children.
====Pricing====
*Harry Potter paid seven Galleons for his wand at Ollivanders.
*There were seven letters in both 'Sickles' and 'Galleon'.
====Hogwarts====
*Children went to school at Hogwarts for seven years.
*There were seven floors at Hogwarts.
*There were seven core classes, which were taught at Hogwarts:
*#Astronomy
*#Charms
*#Defence Against the Dark Arts
*#Herbology
*#History of Magic
*#Potions
*#Transfiguration
*The Marauder's Map showed seven secret passages out of the school (the map did not show the Room of Requirement).
====Quidditch====
*There were seven hundred fouls in Quidditch.
*There were seven players on a Quidditch team.
*There was a broomstick named Cleansweep Seven.
*Harry caught seven Golden Snitches during his time as Seeker on the Gryffindor Quidditch team:
**First year: Gryffindor vs. Slytherin and Gryffindor vs. Hufflepuff
**Second year: Gryffindor vs. Slytherin
**Third year: Gryffindor vs. Ravenclaw and Gryffindor vs. Slytherin
**Fifth year: Gryffindor vs. Slytherin
**Sixth year: Gryffindor vs. Slytherin
====Potions====
*There were seven ingredients of Polyjuice Potion.
*#Fluxweed
*#Knotgrass
*#Lacewing flies
*#Leeches
*#Powdered Bicorn Horn
*#Shredded Boomslang Skin
*#A piece of the person you wanted to turn into (usually hair).
====Books/Publications====
*Gilderoy Lockhart assigned seven books for his students in the 1992–1993 school year:
*#Break with a Banshee
*#Gadding with Ghouls
*#Holidays with Hags
*#Travels with Trolls
*#Voyages with Vampires
*#Wanderings with Werewolves
*#Year with the Yeti
*Hermione Granger stated that 'Alohomora' was in chapter seven of The Standard Book of Spells.
*There were (most likely) seven Standard Book of Spells, one for each year.
====Spells====
*The Unforgivable Curses were first classified as Unforgivable in 1717.
*Many spells such as Protego, Reducto, Imperio, Expulso, Depulso, Anapneo, and Stupefy had seven letters in their incantations.
*There were seven known spell types:
*#Transfiguration
*#Charm
*#Jinx
*#Hex
*#Curse
*#Counter-spell
*#Healing spell
====Miscellaneous====
*The prophecy about Harry Potter defeating Tom Riddle noted that: "The one with the power to vanquish the Dark Lord approaches ... born to those who have thrice defied him, born as the seventh month dies ... and the Dark Lord will mark him as his equal...".
*In the wizarding world, wizards and witches came of age at the age of seventeen, instead of eighteen.
*Seven people came out of the Shrieking Shack in 1994 after Peter Pettigrew's crimes were uncovered:
*#Harry Potter
*#Hermione Granger
*#Peter Pettigrew
*#Remus Lupin
*#Ronald Weasley
*#Sirius Black
*#Severus Snape
*There were seven obstacles leading up to the Philosopher's Stone:
*#Hagrid's pet, Fluffy
*#Sprout's Devil's Snare
*#Flitwick's flying keys
*#McGonagall's giant chess set
*#Quirrell's troll
*#Snape's Potion riddle
*#The Mirror of Erised
*The Philosopher's Stone was kept in Vault 713 in Gringotts Bank.
*Seven entities were attacked by the Basilisk during the 1992–1993 school year:
*#Mrs Norris
*#Colin Creevey
*#Justin Finch-Fletchley
*#Nicholas de Mimsy-Porpington
*#Hermione Granger
*#Penelope Clearwater
*#Harry Potter
*There were seven snakes on the door of the Chamber of Secrets.
*Seven Muggles saw Ron and Harry in the Flying Ford Anglia.
*Mr Weasley won seven hundred Galleons in the Daily Prophet draw.
*From the Great Hall, Harry, Ron, and Hermione climbed seven staircases to reach the tower that houses Professor Trelawney's classroom at the top.
*Harry was introduced to the Order of the Phoenix when it had nine members, but he did not know who seven of them were beforehand.
*Snape removed seventy points from Gryffindor when Harry showed up at Hogwarts late in 1996 (fifty for lateness and twenty for Harry's Muggle attire).
*Dumbledore showed Harry seven memories about Voldemort's past (including both the fake and real Horcrux memory).
*Voldemort made seven Horcruxes. He deliberately created six Horcruxes, to create a seven-fragment soul (including the piece of soul in his body). The singular of Horcruxes (Horcrux) is seven letters long.
*#Tom Riddle's Diary
*#Marvolo Gaunt's Ring
*#Rowena Ravenclaw's Diadem
*#Salazar Slytherin's Locket
*#Helga Hufflepuff's Cup
*#Harry Potter (unintentionally and unknown to Voldemort)
*#Nagini
*There were seven "Potters" during the Battle of the Seven Potters:
*#Harry Potter
*#Ron Weasley
*#Hermione Granger
*#Fred Weasley
*#George Weasley
*#Fleur Delacour
*#Mundungus Fletcher
*There were also seven main conflicts, in Harry Potter's perspective, between 1997-1998, the latter part of the Second Wizarding War:
*Seven prisoners escaped from Malfoy Manor:
*#Mr Ollivander
*#Luna Lovegood
*#Dean Thomas
*#Griphook
*#Harry Potter
*#Hermione Granger
*#Ronald Weasley
*Harry Potter and Ron Weasley received seven O.W.Ls for their Ordinary Wizarding Level examinations. Hermione Granger continued with seven subjects during her sixth year.
*Harry helped Gryffindor beat Slytherin for the House Cup for the first time in seven years.
*On Christmas Day of 1994, after receiving socks as a present from Harry, Dobby told him that he now had seven pairs of socks.
*Harry Potter's chocolate frog card stated that he was famous for seven reasons:
*#Being the first and only known wizard to have survived the killing curse.
*#Being the youngest seeker in a century, having gained a spot on the Hogwarts Gryffindor Quidditch team in 1991 at only eleven years old.
*#Finding and opening Salazar Slytherin's Chamber of Secrets in his second school year and defeating the monster within, which was a Basilisk.
*#Being the youngest competitor of the Triwizard Tournament and winner of said tournament in 1995.
*#Being the only known Gryffindor student that can speak Parseltongue.
*#Being the last master of death to have united the three Deathly Hallows
*#Defeating the most dangerous dark wizard of all time, Lord Voldemort, in 1998.
*Nicolas Flamel was seven years older than his wife.
*During Harry's hearing in the Ministry (in 1995), Dumbledore stated that clause 7 of the Decree for Reasonable Restriction of Underage Sorcery allowed the use of magic in life-threatening situations.
*There was a total of seven known registered Animagi in the twentieth century.
*Minerva McGonagall became an Animagus by the age of seventeen.
*One of the ingredients for the Animagus potion was a silver teaspoon of dew that had not seen sunlight or been touched by human feet for seven days.
*Wendelin the Weird was captured and burnt at the stake forty-seven times.
*In Harry Potter's copy of , he wrote in the Pixie section for the classification, and put seven X's: "or XXXXXXX if you're Lockhart."
==Behind the scenes==
====Dates====
*The first book was released in 1997, and the final book was released in 2007.
*The epilogue itself is set in 2017.
*Many fans expected (the seventh book) to be released on 07/07/2007, which also happened to be a Saturday, the day upon which Harry Potter books had previously been released. However, it was released on July 21st of that year instead, two weeks later. It is thought that the more 'magical' date was rejected due to it also being the second anniversary of the 7/7 London Bombings in 2005. (21 is still a multiple of 7 though.)
*On 7 August, the Harry Potter series won seven awards at the 2011 Teen Choice Awards for Deathly Hallows: Part 1 and Part 2.
*The Battle of Hogwarts in on 2 May, the 2nd day of the 5th month. 2+5 = 7
*The first film in the Fantastic Beasts and Where to Find Them trilogy is set 70 years before the Harry Potter series.
====Chapters====
*There are seventeen chapters in the first book.
*If you count the epilogue, there are thirty-seven chapters in the seventh book.
*The first years enter the castle in the seventh chapter of the first book.
*Chapter four of is entitled "The Seven Potters".
*There are seven books in the Harry Potter series, and eight movies.
====Actors====
*In the films, Voldemort is played by seven actors: Richard Bremmer, Ian Hart, Christian Coulson, Ralph Fiennes, Hero Fiennes-Tiffin, Frank Dillane and by Michael Berendt although the latter's scenes were cut and never seen.Michael Berendt's website.
*J. K. Rowling stated in interview that the "big seven" in the Harry Potter series are: Harry Potter (Daniel Radcliffe), Hermione Granger (Emma Watson), Ron Weasley (Rupert Grint), Ginny Weasley (Bonnie Wright), Neville Longbottom (Matt Lewis), Luna Lovegood (Evanna Lynch), and Draco Malfoy (Tom Felton).SnitchSeeker - J.K. Rowling Talks Harry Potter and the Deathly Hallows: Part 2
====Miscellaneous====
*The number on the back of Harry Potter's Quidditch robes in the films is seven (this could be a reference to the fact that usually the best player/captain in a football team, has the number 7 shirt).
*J. K. Rowling stated in interview that she chose to write seven books in total because she spent seven years in . Also, she wanted Harry to come of age at seventeen because it "just seems a good number for a wizard to come of age."
*In , J.K. split the dedication in seven parts.
*There were seven clues and seven opportunities to sign up and register for the beta. The first clue was on 31 July 2011 (Harry's birthday) and the final was 6 August 2011. A clue was released each day and each clue was from a book in the series corresponding to the day. For example, day one's clue was from Philosopher's Stone and the final clue was from Deathly Hallows.
*Seven is also a unique number, being the highest, single-digit prime number.
==Appearances==
* 
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
==External links==
*
==Notes and references==
Category:Real-Magic
Category:Mathematics