7

Source: Wikipedia, the free encyclopedia.
(Redirected from
7 (number)
)
← 6
7
8 →
Malayalam

7 (seven) is the natural number following 6 and preceding 8. It is the only prime number preceding a cube.

As an early

Vietnamese culture, the number seven is sometimes considered unlucky.[citation needed
]

It is the first natural number whose pronunciation contains more than one syllable.

Evolution of the Arabic digit

SevenGlyph.svg

In the

one
in writing that uses a long upstroke in the glyph for 1. In some Greek dialects of the early 12th century the longer line diagonal was drawn in a rather semicircular transverse line.

Digital77.svg

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.

Sevens.svg

While the shape of the character for the digit 7 has an

TextFigs078.svg
.

Hand Written 7.svg

Most people in Continental Europe,[2] 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,[3] France,[4] Italy, Belgium, Finland,[5] Romania, Germany, Greece,[6] and Hungary.[citation needed

]

Mathematics

Seven, the fourth

safe prime (the only Mersenne safe prime), a Leyland prime of the second kind and the fourth Heegner number.[13]

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.
  • 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.[20] The opposite sides of a standard six-sided dice always add to 7.
  • The
    unsolved.[22]

Basic calculations

Multiplication 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 25 50 100 1000
7 × x 7 14 21 28 35 42 49 56 63 70 77 84 91 98 105 175
350
700 7000
Division 1 2 3 4 5 6 7 8 9 10
11 12 13 14 15
7 ÷ x 7 3.5 2.3 1.75 1.4 1.16 1 0.875 0.7 0.7
0.63 0.583 0.538461 0.5 0.46
x ÷ 7 0.142857 0.285714 0.428571 0.571428 0.714285 0.857142 1 1.142857 1.285714 1.428571
1.571428 1.714285 1.857142
2
2.142857
Exponentiation 1 2 3 4 5 6 7 8 9 10
7x 7 49
343
2401 16807 117649 823543 5764801 40353607 282475249
x7 1 128 2187 16384 78125 279936 823543 2097152 4782969
10000000
Radix 1 5 10 15 20 25 30 40 50 60 70 80 90 100
110 120 130 140 150 200 250 500 1000 10000 100000 1000000
x7 1 5 137 217 267 347 427 557 1017 1147 1307 1437 1567 2027
2157 2317 2447 2607 3037 4047 5057 13137 26267 411047 5643557 113333117

In science

In Psychology

  • 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.[23][24]
  • When guessing numbers 1-10 the number 7 is most likely to be picked.[25]
  • Seven-year itch: happiness in marriage said to decline after 7 years

Classical antiquity

The

Pythagoreans invested particular numbers with unique spiritual properties. The number seven was considered to be particularly interesting because it consisted of the union of the physical (number 4) with the spiritual (number 3).[26] In Pythagorean numerology
the number 7 means spirituality.

References from classical antiquity to the number seven include:

Religion and mythology

Judaism

The number seven forms a widespread

Hebrew scripture
, including:

  • 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
    chuppah
    during 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

Christianity

Following the traditional of the

typological
pattern:

Seven lampstands in The Vision of John on Patmos by Julius Schnorr von Carolsfeld
, 1860

References to the number seven in Christian knowledge and practice include:

Islam

References to the number seven in Islamic knowledge and practice include:

Hinduism

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
    Chakras
    in eastern philosophy
  • Seven stars in a constellation called "
    Saptharishi
    Mandalam" 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[28][29]
  • Seven hills at Tirumala known as Yedu Kondalavadu in Telugu, or ezhu malaiyan in Tamil, meaning "Sevenhills God"
  • Seven steps taken by the
    Buddha
    at birth
  • Seven divine ancestresses of humankind in Khasi mythology
  • Seven octets or
    Ragas
    compositions
  • Seven Social Sins listed by Mahatma Gandhi

Eastern tradition

Other references to the number seven in Eastern traditions include:

Other references

Other references to the number seven in traditions from around the world include:

In culture

In literature

In sports

  • 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.

See also

Notes

  1. ^ 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
  2. ^ 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.
  3. ^ "Education writing numerals in grade 1." Archived 2008-10-02 at the Wayback Machine(Russian)
  4. ^ "Example of teaching materials for pre-schoolers"(French)
  5. ^ Elli Harju (August 6, 2015). ""Nenosen seiska" teki paluun: Tiesitkö, mistä poikkiviiva on peräisin?". Iltalehti (in Finnish).
  6. ^ "Μαθηματικά Α' Δημοτικού" [Mathematics for the First Grade] (PDF) (in Greek). Ministry of Education, Research, and Religions. p. 33. Retrieved May 7, 2018.
  7. ^ Weisstein, Eric W. "Double Mersenne Number". mathworld.wolfram.com. Retrieved 2020-08-06.
  8. ^ "Sloane's A088165 : NSW primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
  9. ^ "Sloane's A050918 : Woodall primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
  10. ^ "Sloane's A088054 : Factorial primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
  11. ^ "Sloane's A031157 : Numbers that are both lucky and prime". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
  12. ^ "Sloane's A035497 : Happy primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
  13. ^ "Sloane's A003173 : Heegner numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
  14. ^ Bryan Bunch, The Kingdom of Infinite Number. New York: W. H. Freeman & Company (2000): 82
  15. ^ Weisstein, Eric W. "Heptagon". mathworld.wolfram.com. Retrieved 2020-08-25.
  16. ^ Weisstein, Eric W. "7". mathworld.wolfram.com. Retrieved 2020-08-07.
  17. ^ "Sloane's A003215 : Hex (or centered hexagonal) numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
  18. . A frieze pattern can be classified into one of the 7 frieze groups...
  19. . ...every catastrophe can be composed from the set of so called elementary catastrophes, which are of seven fundamental types.
  20. ^ Weisstein, Eric W. "Dice". mathworld.wolfram.com. Retrieved 2020-08-25.
  21. ^ "Millennium Problems | Clay Mathematics Institute". www.claymath.org. Retrieved 2020-08-25.
  22. ^ "Poincaré Conjecture | Clay Mathematics Institute". 2013-12-15. Archived from the original on 2013-12-15. Retrieved 2020-08-25.
  23. ^ Gonzalez, Robbie. "Why Do People Love The Number Seven?". Gizmodo. Retrieved 20 February 2022.
  24. ^ Bellos, Alex. "The World's Most Popular Numbers [Excerpt]". Scientific American. Retrieved 20 February 2022.
  25. . Retrieved 20 February 2022.
  26. ^ "Number symbolism - 7".
  27. , retrieved 2020-11-17
  28. .
  29. .
  30. ^ "Encyclopædia Britannica "Number Symbolism"". Britannica.com. Retrieved 2012-09-07.
  31. ISSN 0235-716X
    .
  32. ^ "Chapter I. The Creative Thesis of Perfection by William S. Sadler, Jr. - Urantia Book - Urantia Foundation". urantia.org. 17 August 2011.
  33. ^ Yemaya. Santeria Church of the Orishas. Retrieved 25 November 2022

References