11 (eleven) is the natural number following 10 and preceding 12. In English, it is the smallest positive integer whose name has three syllables.

← 10 11 12 →
Cardinaleleven
Ordinal11th
(eleventh)
Numeral systemundecimal
Factorizationprime
Prime5th
Divisors1, 11
Greek numeralΙΑ´
Roman numeralXI
Greek prefixhendeca-/hendeka-
Latin prefixundeca-
Binary10112
Ternary1023
Senary156
Octal138
DuodecimalB12
HexadecimalB16
Bangla১১
Hebrew numeralי"א
Devanagari numerals११
Malayalam൰൧
Tamil numeralsகக
Telugu౧౧
Babylonian numeral𒌋𒐕

Name

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"Eleven" derives from the Old English ęndleofon, which is first attested in Bede's late 9th-century Ecclesiastical History of the English People.[2][3] It has cognates in every Germanic language (for example, German elf), whose Proto-Germanic ancestor has been reconstructed as *ainalifa-,[4] from the prefix *aina- (adjectival "one") and suffix *-lifa-, of uncertain meaning.[3] It is sometimes compared with the Lithuanian vienúolika, though -lika is used as the suffix for all numbers from 11 to 19.[3]

The Old English form has closer cognates in Old Frisian, Saxon, and Norse, whose ancestor has been reconstructed as *ainlifun. This was formerly thought to be derived from Proto-Germanic *tehun ("ten");[3][5] it is now sometimes connected with *leikʷ- or *leip- ("left; remaining"), with the implicit meaning that "one is left" after counting to ten.[3]

Mathematics

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11 is a prime number, and a super-prime. 11 forms a twin prime with 13,[6] and sexy pair with 5 and 17.

The first prime exponent that does not yield a Mersenne prime is 11.

11 is part of a pair of Brown numbers. Only three such pairs of numbers are known.[citation needed] Rows in Pascal's triangle can be seen as representation of powers of 11.[7]

Geometry

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Copper engraving of a hendecagon, by Anton Ernst Burkhard von Birckenstein (1698)

An 11-sided polygon is called a hendecagon, or undecagon. A regular hendecagon is the polygon with the fewest number of sides that is not able to be constructed with a straightedge, compass, and angle trisector.[8]

The Mathieu group   is the smallest of twenty-six sporadic groups. It has order  , with 11 as its largest prime factor.   is the maximal subgroup Mathieu group  , where 11 is also its largest prime factor.[citation needed]

List of basic calculations

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Multiplication 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 25 50 100 1000
11 × x 11 22 33 44 55 66 77 88 99 110 121 132 143 154 165 176 187 198 209 220 275 550 1100 11000
Division 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
11 ÷ x 11 5.5 3.6 2.75 2.2 1.83 1.571428 1.375 1.2 1.1 1 0.916 0.846153 0.7857142 0.73
x ÷ 11 0.09 0.18 0.27 0.36 0.45 0.54 0.63 0.72 0.81 0.90 1 1.09 1.18 1.27 1.36
Exponentiation 1 2 3 4 5 6 7 8 9 10 11
11x 11 121 1331 14641 161051 1771561 19487171 214358881 2357947691 25937424601 285311670611
x11 1 2048 177147 4194304 48828125 362797056 1977326743 8589934592 31381059609 100000000000 285311670611

Science

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In chemistry, Group 11 of the Periodic Table of the Elements (IUPAC numbering) consists of the three coinage metals copper, silver, and gold known from antiquity, and roentgenium, a recently synthesized superheavy element. 11 is the number of spacetime dimensions in M-theory.

In astronomy

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Apollo 11 was the first crewed spacecraft to land on the Moon. In our solar system, the Sun has a sunspot cycle's periodicity that is approximately 11 years.

Music

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The interval of an octave plus a fourth is an 11th. A complete 11th chord has almost every note of a diatonic scale. Regarding musical instruments, there are 11 thumb keys on a bassoon, not counting the whisper key. (A few bassoons have a 12th thumb key.)

Sports and games

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In sports, there are 11 players on an association football (soccer) team, 11 players on an American football team during play, 11 players on a cricket team on the field, and 11 players in a field hockey team. In the game of blackjack, an ace can count as either one or 11, whichever is more advantageous for the player.

Cultural references

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Film

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In the mockumentary film This Is Spinal Tap, the idiomatic phrase up to eleven is coined to allude to going beyond the limitations of a system, in this case music amplifier volume levels.

In Canada

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The stylized maple leaf on the Flag of Canada has 11 points. The CA$ one-dollar loonie is in the shape of an 11-sided hendecagon, and clocks depicted on Canadian currency, like the Canadian 50-dollar bill, show 11:00.

"Eleventh hour"

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Being one hour before 12:00, the eleventh hour means the last possible moment to take care of something, and often implies a situation of urgent danger or emergency (see Doomsday clock). "The eleventh hour" is a phrase in the Parable of the Workers in the Vineyard in the Bible.

Languages

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While 11 has its own name in Germanic languages such as English, German, or Swedish, and some Latin-based languages such as Spanish, Portuguese, and French, it is the first compound number in many other languages: Chinese 十一 shí yī, Korean 열하나 yeol hana or 십일 ship il.

Mysticism

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The number 11 (alongside its multiples 22 and 33) are master numbers in numerology, especially in New Age.[9]

References

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  1. ^ Bede, Eccl. Hist., Bk. V, Ch. xviii.
  2. ^ Specifically, in the line jjvjv ðæt rice hæfde endleofan wintra.[1]
  3. ^ a b c d e Oxford English Dictionary, 1st ed. "eleven, adj. and n." Oxford University Press (Oxford), 1891.
  4. ^ Kroonen, Guus (2013). Etymological Dictionary of Proto-Germanic. Leiden: Brill. p. 11f. ISBN 978-90-04-18340-7.
  5. ^ Dantzig, Tobias (1930), Number: The Language of Science.
  6. ^ Sloane, N. J. A. (ed.). "Sequence A001359 (Lesser of twin primes.)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2023-01-22.
  7. ^ Mueller, Francis J. (1965). "More on Pascal's Triangle and powers of 11". The Mathematics Teacher. 58 (5): 425–428. doi:10.5951/MT.58.5.0425. JSTOR 27957164.
  8. ^ Gleason, Andrew M. (1988). "Angle trisection, the heptagon, and the triskaidecagon". American Mathematical Monthly. 95 (3). Taylor & Francis, Ltd: 191–194. doi:10.2307/2323624. JSTOR 2323624. MR 0935432. S2CID 119831032.
  9. ^ Sharp, Damian (2001). Simple Numerology: A Simple Wisdom book (A Simple Wisdom Book series). Red Wheel. p. 7. ISBN 978-1-57324-560-9.
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Grimes, James. "Eleven". Numberphile. Brady Haran. Archived from the original on 2017-10-15. Retrieved 2016-01-03.