- 11 (number)
Number|number = 11

range = 10s

cardinal = eleven

ordinal = th

ordinal text =

numeral =undecimal

factorization = prime

prime =

divisor = 1, 11

roman = XI

unicode =

greek prefix = (from Greek)

latin prefix = (fromLatin )

bin = 1011

oct = 102

duo = B

hex = B

misc =**11**(**eleven**) is thenatural number following 10 and preceding 12. It is the first number which cannot be represented by ahuman counting his or her eightfinger s and twothumb s additively (although it can be represented in a variety of other ways using human bodily parts, such as counting additively with the twentydigit s including thetoe s, using the**thumb**to count the finger phalanges of one hand additively up to twelve, or using the fingers in one hand to count up to fifteen binarily). Eleven is the smallest positive integer requiring three syllables in English, and it is also the largest prime number with a single-morpheme name in this language (although etymologically the word "eleven" originated from a Germanic compound *"ainlif" meaning "one left" [*http://www.bartleby.com/61/62/E0086200.html*] ).**In mathematics**Eleven is the 5th smallest

prime number . It is the smallest two-digit prime number in thedecimal base; as well as, of course, inundecimal (where it is the smallest two-digit number). It is also the smallest three-digit prime internary , and the smallest four-digit prime in binary, but a single-digit prime in bases larger than ten, such asduodecimal ,hexadecimal ,vigesimal andsexagesimal . 11 is the fourthSophie Germain prime , the thirdsafe prime , the fourthLucas prime , and the firstrepunit prime . Although it is necessary for n to be prime for 2^{n}-1 to be aMersenne prime , the converse is not true: 2^{11}- 1 = 2047 which is 23 × 89. The next prime is 13, with which it comprises atwin prime . 11 is anEisenstein prime with no imaginary part and real part of the form $3n\; -\; 1$. Displayed on a calculator, 11 is astrobogrammatic prime and adihedral prime because it reads the same whether the calculator is turned upside down or reflected on a mirror, or both.Because it has a reciprocal of unique period length among primes, 11 is the second

unique prime . 11 goes into 99 exactly 9 times, sovulgar fraction s with 11 in thedenominator have two digit repeating sequences in theirdecimal expansions. Multiples of eleven by one-digit numbers all have double digits: 00 (=0), 11, 22, 33, 44 . . .Eleven is the

Aliquot sum of one number, the discretebiprime 21 and is the base of the 11-aliquot tree.As 11 is the smallest factor of the first eleven terms of the

Euclid-Mullin sequence , it is the twelfth term.An eleven-sided

polygon is called ahendecagon orundecagon .In both base 6 and base 8, the smallest prime with a composite sum of digits is 11.

In base 10, there is a simple test to determine if an integer is divisible by 11: take every digit of the number located in odd position and add them up, then take the remaining digits and add them up. If the difference between the two sums is a multiple of 11, including 0, then the number is divisible by 11. For instance, if the number is 65,637 then (6 + 6 + 7) - (5 + 3) = 19 - 8 = 11, so 65,637 is divisible by eleven. This technique also works with groups of digits rather than individual digits, so long as the number of digits in each group is odd, although not all groups have to have the same number of digits. For instance, if one uses three digits in each group, one gets from 65,637 the calculation (065) - 637 = -572, which is divisible by eleven.

Another test for divisibility is to separate a number into groups of two consecutive digits (adding a leading zero if there is an odd number of digits), and then add up the numbers so formed; if the result is divisible by eleven, the number is divisible by eleven. For instance, if the number is 65,637, 06 + 56 + 37 = 99, which is divisible by eleven, so 65,637 is divisible by eleven. This also works by adding a trailing zero instead of a leading one: 65 + 63 + 70 = 198, which is divisible by eleven. This also works with larger groups of digits, providing that each group has an even number of digits (not all groups have to have the same number of digits).

An easy way of

multiply ing numbers by 11 in base 10 is:If the number has:

*1 digit - Replicate the digit (so 2 x 11 becomes 22).

*2 digits - Add the 2 digits together and place the result in the middle (so 47 x 11 becomes 4 (11) 7 or 4 (10+1) 7 or (4+1) 1 7 or 517).

*3 digits - Keep the first digit in its place for the result's first digit, add the first and second digits together to form the result's second digit, add the second and third digits together to form the result's third digit, and keep the third digit as the result's fourth digit. For any resulting numbers greater than 9, carry the 1 to the left. Example 1: 123 x 11 becomes 1 (1+2) (2+3) 3 or 1353. Example 2: 481 x 11 becomes 4 (4+8) (8+1) 1 or 4 (10+2) 9 1 or (4+1) 2 9 1 or 5291.

*4 or more digits - Follow the same pattern as for 3 digits.In base 10, 11 is the only integer that is not a

Nivenmorphic number .In base thirteen and higher bases (such as

hexadecimal ), eleven is represented as B, where ten is A. Induodecimal , however, eleven is sometimes represented as E and ten as T.Multiplied by num/neg|1, eleven is a

Heegner number .There are 11 orthogonal curvilinear

coordinate systems (to within a conformal symmetry) in which the 3-variableHelmholtz equation can be solved using theseparation of variables technique.See also

11-cell .**List of basic calculations****List of basic operations that make 11****In science***The

atomic number ofsodium .

*In chemistry, Group**11**includes the three coinage metalscopper ,silver , andgold known from antiquity.

*The number ofspacetime dimension s inM-theory .**Astronomy***

Apollo 11 was the first manned spacecraft to land on theMoon .*The approximate periodicity of a

sunspot cycle is 11 years.*

Messier object M11, a magnitude 7.0open cluster in the constellationScutum , also known as theWild Duck Cluster .*The

New General Catalogue [*http://www.ngcic.org/ object*]NGC 11 , aspiral galaxy in theconstellation Andromeda*The

Saros [*http://sunearth.gsfc.nasa.gov/eclipse/LEsaros/LEsaros1-175.html number*] of thesolar eclipse series which began on-2511 December 26 and ended on-1158 March 18 . The duration of Saros series 11 was 1352.2 years, and it contained 76 solar eclipses.*The Saros [

*http://sunearth.gsfc.nasa.gov/eclipse/LEsaros/LEsaros1-175.html number*] of thelunar eclipse series which began on-2389 June 19 and ended on-1037 September 8 . The duration of Saros series 11 was 1352.2 years, and it contained 76 lunar eclipses.*The 11th moon of Jupiter is Himalia.

**In music***The interval of an

octave and a fourth is an eleventh. A complete eleventh chord has almost every note of adiatonic scale .

*The number of thumb keys on abassoon , not counting the whisper key. (A few bassoons have a twelfth thumb key.)

*Spinal Tap 's amplifiers goup to eleven , every other bands' just go to ten, but it doesn't actually amplify the sound any greater.

*Maria Taylor's Debut solo album is entitled 11:11

*The All-American Rejects have a song on the CD Move Along that is called 11:11

*Andrew Bird has a song called 11:11

*The title ofBryan Adams ' newest album is 11.

*The songJimmy , by the bandTool mentions the number 11, in reference to a stroke suffered by lead singerMaynard James Keenan 's mother when he was 11 years old; it also refers to the number of dimensions inM Theory andString Theory .**In sports**There are eleven players on a soccer team on the field at a time as well as in a

cricket team. Within a school or college, the phrases "the football XI" and "the cricket XI" generally refer to the first (best) team currently playing.Other teams are often referred to as "the second XI" etc.Also in soccer, in the German language (and possibly others, in countries that predominantly use the metric system) a penalty kick is referred to as "Elfmeter" because the penalty spot is approximately 11m (precisely 12 yards) from the goal line. Historically, in the Pyramid formation that position names are taken from, a left wing-forward in football wears number 11. In the modern game, especially using the 4-4-2 formation, it is worn by a left-sided

midfielder . Less commonly astriker will wear the shirt.There are eleven players in a

field hockey team. The player wearing 11 will usually play on the left-hand side, as in soccer.An

American football team also has eleven players on the field at one time during play. 11 is also worn byquarterback s, kickers, punter andwide receiver s inAmerican football 'sNFL . The only NFL team that has retired the #11 is the New York Giants, in honor of quarterbackPhil Simms .In

rugby union the left wing wears the 11 shirt.Jonah Lomu wore the number when he played for theAll Blacks as he played left wing (see rugby union above).In

rugby league , the 11 shirt is worn by a second-row forward.In cricket, 11 is the number of players from the fielding (or bowling) side on the field of play at any one time. The eleventh batsman is usually the weakest batsman, at the end of the tail. He is primarily in the team for his bowling abilities.

The car number 11 was driven by

Ayrton Senna as he won the 1988Formula One World Championship. AlsoDarrell Waltrip andCale Yarborough used the number when they won theirNASCAR Winston Cup Series championships.**In the military***The number of guns in a gun

salute to U.S. Army, Air Force and Marine Corps Brigadier Generals, and to Navy and Coast Guard Rear Admirals Lower Half.

*TheMilitary Occupational Specialty (MOS) designator given to US Army Infantry (AKA 11 Series, or 11B, 11C, 11D, 11H, 11M, etc)

*The number of General Orders for Sentries in the Marine Corps andUnited States Navy .

*A page in the Service Record Book of an enlisted Marine for writing down disciplinary actions.

*World War I ended with an Armistice onNovember 11 ,1918 , which went into effect at 11:00 am-the 11th hour on the 11th day of the 11th month of the year.Armistice Day is still observed onNovember 11 of each year, although it is now calledVeteran's Day in the United States andRemembrance Day in theCommonwealth of Nations and parts of Europe.**In technology*** In

Mozilla Firefox , Opera,Konqueror forKDE , andInternet Explorer 4 and later [*[*] for Windows, the*http://www.microsoft.com/enable/products/KeyboardSearch_IE4.aspx Keyboard Shortcuts for Internet Explorer 4*]function key F11 key toggles full screen viewing mode. InMac OS X , F11 hides all open windows.

* The windowing system forUnix computers is known asX11 .**Canada*** The stylized maple leaf on the

Flag of Canada has eleven points.

* The Canadian one-dollar coin is ahendecagon , an eleven-sided polygon.

* Clocks depicted on Canadian currency, for example theCanadian fifty-dollar bill , show 11:00.

* Eleven denominations of Canadian currency are produced in large quantities.

* Due to Canada's federal nature, eleven legally distinct Crowns effectively exist in the country, with the Monarch being represented separately in each province, as well as at the federal level.**In other fields***Three films -- "Ben-Hur" (1959), "Titanic" (1997), and "" (2003) -- have each won eleven

Academy Awards , includingBest Picture of their respective years.

*The number eleven is important innumerology , as it is the first of the "Master Numbers".

*Being only one hour before 12:00—midnight —the "eleventh hour " means the last possible moment to take care of something, and often implies a situation of urgent danger or emergency (seeDoomsday clock ).

*InAstrology , Aquarius is the 11thastrological sign of theZodiac .

*In the film "This Is Spinal Tap ," guitaristNigel Tufnel proudly shows off anamplifier with top settings of 11, higher than the traditional 10. The phrase "" or "Up to eleven **These go to eleven**" inpopular culture has come to refer to anything capable of being exploited to its utmost abilities, or to exceed them, such as a sound volume control. Similarly, the expression "turning it up to eleven" may refer to the act of taking something to an extreme. In 2002 the phrase entered theShorter Oxford English Dictionary with the definition "up to maximum volume" [*http://www.timesonline.co.uk/printFriendly/0%2C%2C1-3564-427663%2C00.html*] .

*"Ocean's Eleven " is the name of two American films.

*In Basque, "hamaika" ("eleven") has the double meaning of "infinite ", probably from "amaigabe", "endless", as in "Hamaika aldiz etortzeko esan dizut!" ("I told you infinite/eleven times to come!").

*American Airlines flight 11 , aBoston -Los Angeles flight which crashed into the North Tower of the World Trade Center after being hijacked by terrorists inNew York, New York onSeptember 11 ,2001 .

* Thenumber 11 bus is a low-cost way ofsightseeing inLondon

* In the game ofblackjack , an Ace can be counted as either one or eleven, whichever is more advantageous for the player.

* Sadra Azizi, nominee for Grand Marshal of RPI, ran on the 11 platform.

* 11 is the number of dimensions in M theory

* 11 is the number of the French departmentAude **Historical years****11 A.D.**, 11 B.C.,1911 ,2011 , etc.**ee also***

***References**

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