Seven

"...isn't seven the most powerfully magical number, wouldn't seven-?"

- Tom Riddle discusses the power of the number seven

Seven is the most powerful magical number, based on centuries of mythology, science, and mathematics.

Wizarding community
The Arithmancer Bridget Wenlock (1202–1285) was the first witch to establish the magical properties of the number seven.

Seven is the age by which most experts believe that magic will reveal itself in a wizard or witch. In the life of the Hogwarts School of Witchcraft and Wizardry community, it is the number of years students must attend Hogwarts before graduating. There were seven chambers protecting the Philosopher's Stone. Lord Voldemort was such a believer in the magical properties of the number seven that he intended to split his soul into seven portions by creating six Horcruxes. Ironically, he instead succeeded in creating seven Horcruxes, thus splitting his soul eight ways - however, by pure chance, only six of his Horcruxes ever existed at one time (as the Diary was destroyed before Nagini became a Horcrux). Harry Potter and Neville Longbottom were born in July, the seventh month of the year; this made them both potential subjects of a prophecy. Arthur and Molly Weasley had seven children; Ginny Weasley is the seventh of them, and the only daughter. There are also seven players on a standard Quidditch team, with seven also being the number on Harry Potter's Quidditch uniform. During the Battle over Little Whinging, six others took Polyjuice Potion in order to take on Harry's appearance as a diversion, thus there were "seven Potters."

Seven seen in the Wizarding world

 * S.P.T to A.P.W.B.D: "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......"
 * Molly and Arthur Weasley had seven children.
 * Ginny Weasley is the seventh child of Molly and Arthur.
 * "Dragon liver, seven teen Sickles an ounce, they're mad..." - Diagon Alley witch
 * Ginny Weasley is the first girl born to the Weasleys in seven generations.
 * Thaddeus Thurkell had seven children, all Squibs.
 * Walter Parkin has seven children.
 * Before Harry Potter and Ronald Weasley came of age, seven people owned pocket watch.
 * Children go to school at Hogwarts for seven years.
 * There are seven floors at Hogwarts.
 * In the wizarding world, wizards and witches come of age at the age of seventeen, instead of eighteen.
 * Harry Potter paid 7 Galleons for his wand.
 * There are seven hundred fouls in Quidditch.
 * There are seven players on a Quidditch team
 * The wolfsbane potion must be drunk every 7 days before full moon.
 * The found index finger of Peter Pettigrew is the 7th finger if you count from 1 to 10.
 * Seven people come out of the Shrieking Shack in 1994 after Peter Pettigrew's crimes are uncovered:
 * Harry Potter
 * Ronald Weasley
 * Hermione Granger
 * Remus Lupin
 * Sirius Black
 * Severus Snape
 * Peter Pettigrew


 * There are seven puzzles 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 Potions
 * The Mirror of Erised


 * 7 Ghosts of Hogwarts mentioned more than once:
 * Nearly Headless Nick
 * The Grey Lady
 * The Fat Friar
 * The Bloody Baron
 * Peeves the Poltergeist
 * Professor Binns
 * Moaning Myrtle


 * In Philosopher's Stone, Hermione says that the spell 'Alohomora' was in The Standard Book of Spells chapter 7.
 * 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 are 7 snakes on the door of the Chamber of Secrets.
 * There are 7 locks on Professor Moody's trunk
 * Seven teen silver Sickles to a Galleon
 * Broomstick named Cleansweep Seven
 * Seven bottles in the last task in the Philosopher's Stone chambers
 * Seven muggles saw Ron and Harry in the Flying Ford Anglia
 * Seven keepers for every dragon for the first task of the Triwizard Tournament
 * Mr. Weasley won seven hundred galleons in the Daily Prophet drawing
 * Harry helped Gryffindor beat Slytherin for the House Cup for the first time in seven years
 * Only seven people knew where the entrance to the Chamber of Secrets was before the Basilisk within was killed.
 * Salazar Slytherin
 * Tom Riddle
 * Myrtle
 * Harry Potter
 * Ron Weasley
 * Ginny Weasley
 * Gilderoy Lockhart


 * There are seven registered Animagi of the 20th century:
 * Minerva McGonagall — Tabby cat
 * Unidentified witch — Cat
 * 5 unknown animagi — Forms unknown


 * The Marauder's Map shows seven secret passages out of the school.
 * From the Great Hall, Harry, Ron, and Hermione climb seven staircases to reach the tower that houses Professor Trelawney's classroom at the top.
 * Out of the nine members of the Order of the Phoenix in the Advance Guard Harry hadn't already been acquainted with seven of them beforehand.
 * The mother of Blaise Zabini had been married seven times as of 1996.
 * In 1996, while brewing the Draught of Living Death in a Potions class, Harry followed the alternate instructions in the Half-Blood Prince's copy of Advanced Potion-Making, by stirring his potion once clockwise after every seventh stir counter-clockwise. This helped him achieve much better results than the standard instructions, and earn Slughorn's praise.
 * Marvolo, Tom Riddle's middle name has seven letters in it.
 * Voldemort made seven Horcruxes, even though he believed that six Horcruxes would create a seven-fragment soul (including the piece of soul in his body).
 * 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 are seven "Potters" during the Battle over Little Whinging:
 * Harry Potter
 * Ron Weasley
 * Hermione Granger
 * Fred Weasley
 * George Weasley
 * Fleur Delacour
 * Mundungus Fletcher


 * There are also seven conflicts in Harry Potter and the Deathly Hallows:
 * The Battle over Little Whinging
 * Infiltration of the Ministry of Magic
 * The Attack at Godric's Hollow (1997)
 * Ambush at the Lovegood House
 * The Battle of Malfoy Manor
 * 1998 Break-In of Gringotts Wizarding Bank
 * The Battle of Hogwarts


 * Seven prisoners escape from Malfoy Manor:
 * Mr. Ollivander
 * Luna Lovegood
 * Dean Thomas
 * Griphook
 * Harry Potter
 * Hermione Granger
 * Ron Weasley


 * Harry Potter escaped death at the hands of Lord Voldemort seven times before finishing him off:
 * In Godric's Hollow in 1981
 * Over the Philosopher's Stone while Voldemort was in control of Quirinus Quirrell
 * In the Chamber of Secrets in 1993
 * In Little Hangleton in 1995
 * During the Battle of the Department of Mysteries
 * During the Battle over Little Whinging
 * During the Battle of Hogwarts

Seven in the Harry Potter series

 * There are seven books.
 * The first years enter the castle in the seventh chapter of the first book.
 * Many fans expected Harry Potter and the Deathly Hallows (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.)
 * 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).
 * Chapter four of Harry Potter and the Deathly Hallows is entitled "The Seven Potters".
 * J. K. Rowling stated in interview that she chose to write seven books in total because she spent seven years in secondary school. 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 the seventh Harry Potter book, J.K. split the dedication in seven parts.

Science and nature

 * Seven is a common number in science and nature. It is the number of spots on a common ladybug. All mammals' necks have seven bones, with very few exceptions. September was the seventh month of the calendar before January and February were added.
 * There are seven colours of the rainbow: red, orange, yellow, green, blue, indigo, and violet.
 * Seven is the greatest single digit Prime Number
 * The Native Americans of Montana have seven seasons: chinook season, muddy spring, green summer, gold summer, 'Indian' summer, late fall, and cold winter.
 * In Korea, in one of the speeches of the reverend Moon, this one declared to have already proceeded to the blessing of 777 couples.
 * Seven is the most likely number to be formed by the combined numbers of two regular cubic dice
 * There are seven heavenly bodies visible to the naked eye: Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn. In addition, there are seven stars in the star cluster Pleiades (also called the "seven sisters"), one of which Merope Gaunt was named after.
 * There are seven saints appearing in the constellation "Saptharishi Mandalam" in Indian Astronomy.
 * There are traditionally "seven wonders" of the ancient world. There were seven emperors of the classical age of Rome. In the English history period of 500-850 AD, there are seven kingdoms that would eventually become the Kingdom of England in the 10th century: Northumbria, Mercia, East Anglia, Essex, Kent, Sussex, and Wessex.
 * A common winning combination of most slot machines is 7-7-7, and 7 is a common winning total in traditional dice games.
 * Scientists suggest that most people will fall in love approximately seven times before marriage.
 * Prior to 900AD England was divided into seven kingdoms.

Magic and mysticism

 * The number seven holds great power in the realms of magic and mysticism. In Judaism, the number seven alludes to the infusion of spirituality and Godliness. For example, traditionally it is held that "God rested on and sanctified the seventh day", or Sabbath. Seven blessings are recited under the chuppah during a Jewish wedding ceremony (Sheva Berachot). Moreover, there are the "Seven Shepherds" who visit the sukkah during the holiday of Sukkot: Abraham, Isaac, Jacob, Joseph, Moses, Aaron, and David. There were seven nations promised to the Israelites when they entered the land of Israel. Each seventh year (Shemitah) is holy. each seventh Shemitah (Yovel) is holier than other Shemitahs. The Jewish candlestick (the menorah) has seven branches.
 * The "Devil's Number" 6-6-6 is countered by the combination of 7-7-7 which is "God's Number". This number also joins together the principles of the man, 700, the cosmic plans, 70, and their image in the Archetype, 7, according to R. Allendy. It is the universal organisation, 7 + 7 + 7 = 21, the general evolution.
 * Seven further has a presence in mysticism as Yahweh or Jehovah is the divine name in Christianity, whose letters alphabetically equal seventy, a product of the divine number seven. There are traditionally seven virtues: Chastity, Moderation, Liberality, Charity, Meekness, Zeal, and Humility. Correspondingly, there are seven deadly sins and seven holy sacraments. According to some traditions, there are seven Archangels.
 * In Hindu tradition, there are seven worlds in the universe and seven chakras. In Japanese mythology, there are seven Lucky Gods. In the British folk tale Tam Lin, every seven years the Fairy Queen pays a tithe to Hell. Moreover, in the British tale of of Thomas the Rhymer, he went to live in the faerie kingdom for seven years. There are seven basic principles of Bushido.
 * There were also seven main islands constituting the mythological land of Atlantis.
 * There are seven chakras: Muladhara, Swadhisthana, Manipura, Anahata, Vishuddha, Ajna, and Sahasrara.