As an early
It is the first natural number whose pronunciation contains more than one syllable.
Evolution of the Arabic digit
On the seven-segment displays of pocket calculators and digital watches, 7 is the digit with the most common graphic variation (1, 6 and 9 also have variant glyphs). Most calculators use three line segments, but on Sharp, Casio, and a few other brands of calculators, 7 is written with four line segments because in Japan, Korea and Taiwan 7 is written with a "hook" on the left, as ① in the following illustration.
While the shape of the character for the digit 7 has an
Most people in Continental Europe, and some in Britain and Ireland as well as Latin America, write 7 with a line in the middle ("
7"), sometimes with the top line crooked. The line through the middle is useful to clearly differentiate the digit from the digit one, as the two can appear similar when written in certain styles of handwriting. This form is used in official handwriting rules for primary school in Russia, Ukraine, Bulgaria, Poland, other Slavic countries, France, Italy, Belgium, Finland, Romania, Germany, Greece, and Hungary.[citation needed
Seven, the fourth
- Seven is the lowest natural number that cannot be represented as the sum of the squares of three integers. (See Lagrange's four-square theorem#Historical development.)
- Seven is the 8and is the base of the 7-aliquot tree.
- 7 is the only number D for which the equation 2n − D = x2 has more than two solutions for n and x natural. In particular, the equation 2n − 7 = x2 is known as the Ramanujan–Nagell equation.
- 7 is the only dimension, besides the familiar 3, in which a vector cross product can be defined.
- 7 is the lowest dimension of a known exotic sphere, although there may exist as yet unknown exotic smooth structures on the 4-dimensional sphere.
- denominator is converted to a decimal expansion, the result has the same six-digit repeating sequence after the decimal point, but the sequence can start with any of those six digits.For example, 1/7 = 0.142857 142857... and 2/7 = 0.285714 285714....
- In fact, if one sorts the digits in the number 142,857 in ascending order, 124578, it is possible to know from which of the digits the decimal part of the number is going to begin with. The remainder of dividing any number by 7 will give the position in the sequence 124578 that the decimal part of the resulting number will start. For example, 628 ÷ 7 = 89+5/7; here 5 is the remainder, and would correspond to number 7 in the ranking of the ascending sequence. So in this case, 628 ÷ 7 = 89.714285. Another example, 5238 ÷ 7 = 748+2/7, hence the remainder is 2, and this corresponds to number 2 in the sequence. In this case, 5238 ÷ 7 = 748.285714.
- A seven-sided shape is a
- There are seven isomorphic to the group of integers.
- There are seven fundamental types of catastrophes.
- When rolling two standard six-sided dice, seven has a 6 in 62 (or 1/6) probability of being rolled (1–6, 6–1, 2–5, 5–2, 3–4, or 4–3), the greatest of any number. The opposite sides of a standard six-sided dice always add to 7.
- The unsolved.
|7 × x||7||14||21||28||35||42||49||56||63||70||77||84||91||98||105||175||
|7 ÷ x||7||3.5||2.3||1.75||1.4||1.16||1||0.875||0.7||0.7|
|x ÷ 7||0.142857||0.285714||0.428571||0.571428||0.714285||0.857142||1||1.142857||1.285714||1.428571|
- Seven colors in a rainbow: ROYGBIV
- Seven Continents
- Seven Seas
- Seven climes
- The neutral pH balance
- Number of music notes in a scale
- Number of spots most commonly found on ladybugs
- Atomic number for Nitrogen
- Seven, plus or minus two as a model of working memory.
- Seven Alice A. Bailey
- In Western Culture, Seven is consistently listed as people's favorite number.
- When guessing numbers 1-10 the number 7 is most likely to be picked.
- Seven-year itch: happiness in marriage said to decline after 7 years
References from classical antiquity to the number seven include:
- Seven Seven Heavens
- Seven Wonders of the ancient world
- Seven metals of antiquity
- Seven days in the week
- Seven Seas
- Seven Sages
- Seven champions that fought Thebes
- Seven Kings of Rome
- Seven Sisters, the daughters of Atlas also known as the Pleiades
Religion and mythology
The number seven forms a widespread
- Seven days (more precisely yom) of Creation, leading to the seventh day or Sabbath (Genesis 1)
- Seven-fold vengeance visited on upon Cain for the killing of Abel (Genesis 4:15)
- Seven pairs of every clean animal loaded onto the ark by Noah (Genesis 7:2)
- Seven years of plenty and seven years of famine in Pharaoh's dream (Genesis 41)
- Seventh son of Jacob, Gad, whose name means good luck (Genesis 46:16)
- Seven times bullock's blood is sprinkled before God (Leviticus 4:6)
- Seven nations God told the Israelites they would displace when they entered the land of Israel(Deuteronomy 7:1)
- Seven days of the Passover feast (Exodus 13:3–10)
- Seven-branched Menorah(Exodus 25)
- Seven trumpets played by seven priests for seven days to bring down the walls of Jericho (Joshua 6:8)
- Seven things that are detestable to God (Proverbs 6:16–19)
- Seven Pillars of the House of Wisdom (Proverbs 9:1)
- Seven archangels in the deuterocanonical Book of Tobit (12:15)
References to the number seven in Jewish knowledge and practice include:
- Seven divisions of the weekly readings or aliyah of the Torah
- Seven Jewish men (over the age of 13) called to read aliyahs in Shabbat morning services
- Seven blessings recited under the chuppahduring a Jewish wedding ceremony
- Seven days of festive meals for a Jewish bride and groom after their wedding, known as Sheva Berachot or Seven Blessings
- Seven Ushpizzin prayers to the Jewish patriarchs at during the holiday of Sukkot
Following the traditional of the
- Seven loaves multiplied into seven basketfuls of surplus (Matthew 15:32–37)
- Seven demons were driven out of Mary Magdalene(Luke 8:2)
- Seven last sayings of Jesus on the cross
- Seven men of honest report, full of the Holy Ghost and wisdom (Acts 6:3)
- Seven Seals in the Book of Revelation
References to the number seven in Christian knowledge and practice include:
- Seven Gifts of the Holy Spirit
- Seven Spiritual Acts of Mercy
- Seven deadly sins: lust, gluttony, greed, sloth, wrath, envy, and pride, and seven terraces of Mount Purgatory
- Seven Virtues: chastity, temperance, charity, diligence, kindness, patience, and humility
- Seven Joys and Seven Sorrows of the Virgin Mary
- Seven Sleepers of Christian myth
- Seven Sacramentsin the Catholic Church (though some traditions assign a different number)
References to the number seven in Islamic knowledge and practice include:
- Seven Qur'an
- Seven walks between
- Seven doors to hell (for heaven the number of doors is eight)
- Seventh day naming ceremony held for babies
- Seven enunciators of divine revelation (nāṭiqs) according to the celebrated Fatimid Ismaili dignitary Nasir Khusraw
- Circle Seven Koran, the holy scripture of the Moorish Science Temple of America
References to the number seven in Hindu knowledge and practice include:
- Seven worlds in the universe and seven seas in the world in Hindu cosmology
- Seven sages or Saptarishi and their seven wives or Sapta Matrka in Hindu mythology
- Seven Chakrasin eastern philosophy
- Seven stars in a constellation called "SaptharishiMandalam" in Indian astronomy
- Seven promises, or Saptapadi, and seven circumambulations around a fire at Hindu weddings
- Seven virgin goddesses or Saptha Kannimar worshipped in temples in Tamil Nadu, India
- Seven hills at Tirumala known as Yedu Kondalavadu in Telugu, or ezhu malaiyan in Tamil, meaning "Sevenhills God"
- Seven steps taken by the Buddhaat birth
- Seven divine ancestresses of humankind in Khasi mythology
- Seven octets or Ragascompositions
- Seven Social Sins listed by Mahatma Gandhi
Other references to the number seven in Eastern traditions include:
- Seven Lucky Gods or gods of good fortune in Japanese mythology
- Seven-Branched Sword in Japanese mythology
- Seven Sages of the Bamboo Grove in China
- Seven minor symbols of yin-yang
Other references to the number seven in traditions from around the world include:
- Seven palms in an Egyptian Sacred Cubit
- Seven ranks in Mithraism
- Seven hills of Istanbul
- Seven islands of Atlantis
- Seven Cherokee clans
- Seven lives of cats in Romance language-speaking cultures
- Seven fingers on each hand, seven toes on each foot and seven pupils in each eye of the Irish epic hero Cúchulainn
- Seventh sons will be werewolves in Galician folklore, or the son of a woman and a werewolf in other European folklores
- Seventh sons of a seventh son will be magicians with special powers of healing and clairvoyance in some cultures, or vampires in others
- Seven prominent Guaraní mythology
- Seven gateways traversed by Inanna during her descent into the underworld
- Seven Wise Masters, a cycle of medieval stories
- Seven sister goddesses or fates in Baltic mythology called the Deivės Valdytojos.
- Seven legendary Cities of Gold, such as Cibola, that the Spanish thought existed in South America
- Seven years spent by Thomas the Rhymer in the faerie kingdom in the eponymous British folk tale
- Seven-year cycle in which the Queen of the Fairies pays a tithe to Hell (or possibly Hel) in the tale of Tam Lin
- Bahá'u'lláhin the Bahá'í faith
- Seven superuniverses in the cosmology of Urantia
- Seven Alice A. Bailey
- The sacred number of Yemaya
- Seven Dwarfs
- Seven features prominently in A Song of Ice and Fire by George R. R. Martin, namely, the Seven Kingdoms and the Faith of the Seven
- Sports with seven players per side
- Seven is the least number of players a soccer team must have on the field in order for a match to start and continue.
- A touchdown plus an extra point is worth seven points.
- Diatonic scale (7 notes)
- Seven colors in the rainbow
- Seven continents
- Seven liberal arts
- Seven Wonders of the Ancient World
- Seven days of the Week
- Septenary (numeral system)
- Year Seven (School)
- Se7en (disambiguation)
- Sevens (disambiguation)
- One-seventh area triangle
- Z with stroke (Ƶ)
- List of highways numbered 7
- Georges Ifrah, The Universal History of Numbers: From Prehistory to the Invention of the Computer transl. David Bellos et al. London: The Harvill Press (1998): 395, Fig. 24.67
- Eeva Törmänen (September 8, 2011). "Aamulehti: Opetushallitus harkitsee numero 7 viivan palauttamista". Tekniikka & Talous (in Finnish). Archived from the original on September 17, 2011. Retrieved September 9, 2011.
- "Education writing numerals in grade 1." Archived 2008-10-02 at the Wayback Machine(Russian)
- "Example of teaching materials for pre-schoolers"(French)
- Elli Harju (August 6, 2015). ""Nenosen seiska" teki paluun: Tiesitkö, mistä poikkiviiva on peräisin?". Iltalehti (in Finnish).
- "Μαθηματικά Α' Δημοτικού" [Mathematics for the First Grade] (PDF) (in Greek). Ministry of Education, Research, and Religions. p. 33. Retrieved May 7, 2018.
- Weisstein, Eric W. "Double Mersenne Number". mathworld.wolfram.com. Retrieved 2020-08-06.
- "Sloane's A088165 : NSW primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
- "Sloane's A050918 : Woodall primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
- "Sloane's A088054 : Factorial primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
- "Sloane's A031157 : Numbers that are both lucky and prime". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
- "Sloane's A035497 : Happy primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
- "Sloane's A003173 : Heegner numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
- Bryan Bunch, The Kingdom of Infinite Number. New York: W. H. Freeman & Company (2000): 82
- Weisstein, Eric W. "Heptagon". mathworld.wolfram.com. Retrieved 2020-08-25.
- Weisstein, Eric W. "7". mathworld.wolfram.com. Retrieved 2020-08-07.
- "Sloane's A003215 : Hex (or centered hexagonal) numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
- Weisstein, Eric W. "Dice". mathworld.wolfram.com. Retrieved 2020-08-25.
- "Millennium Problems | Clay Mathematics Institute". www.claymath.org. Retrieved 2020-08-25.
- "Poincaré Conjecture | Clay Mathematics Institute". 2013-12-15. Archived from the original on 2013-12-15. Retrieved 2020-08-25.
- Gonzalez, Robbie. "Why Do People Love The Number Seven?". Gizmodo. Retrieved 20 February 2022.
- Bellos, Alex. "The World's Most Popular Numbers [Excerpt]". Scientific American. Retrieved 20 February 2022.
- "Number symbolism - 7".
- "Encyclopædia Britannica "Number Symbolism"". Britannica.com. Retrieved 2012-09-07.
- "Chapter I. The Creative Thesis of Perfection by William S. Sadler, Jr. - Urantia Book - Urantia Foundation". urantia.org. 17 August 2011.
- Yemaya. Santeria Church of the Orishas. Retrieved 25 November 2022
- Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group (1987): 70–71