11 (number)

Name

"Eleven" derives from the Old English Template:Lang, which is first attested in Bede's late 9th-century Ecclesiastical History of the English People.Template:Refn It has cognates in every Germanic language (for example, German Template:Lang), whose Proto-Germanic ancestor has been reconstructed as Template:Lang, from the prefix Template:Lang (adjectival "one") and suffix Template:Lang, of uncertain meaning. It is sometimes compared with the Lithuanian Template:Lang, though Template:Lang is used as the suffix for all numbers from 11 to 19.

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

Mathematics

11 is a prime number, and a super-prime. 11 forms a twin prime with 13, and sexy pair with 5 and 17. 11 is also the first prime exponent that does not yield a Mersenne prime.

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

Geometry

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.

The Mathieu group ${\mathrm{M}}_{11}$ is the smallest of twenty-six sporadic groups. It has order $7920=2^4\cdot 3^2\cdot 5\cdot 11=8\cdot 9\cdot 10\cdot 11$, with 11 as its largest prime factor. ${\mathrm{M}}_{11}$ is the maximal subgroup Mathieu group ${\mathrm{M}}_{12}$, where 11 is also its largest prime factor.Template:Citation needed

List of basic calculations

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.Template:Overline	2.75	2.2	1.8Template:Overline	1.Template:Overline	1.375	1.Template:Overline	1.1	1	0.91Template:Overline	0.Template:Overline	0.7Template:Overline	0.7Template:Overline
x ÷ 11	0.Template:Overline	0.Template:Overline	0.Template:Overline	0.Template:Overline	0.Template:Overline	0.Template:Overline	0.Template:Overline	0.Template:Overline	0.Template:Overline	0.Template:Overline	1	1.Template:Overline	1.Template:Overline	1.Template:Overline	1.Template:Overline

Exponentiation	1	2	3	4	5	6	7	8	9	10	11
11Template:Sup	11	121	1331	14641	161051	1771561	19487171	214358881	2357947691	25937424601	285311670611
xTemplate:Sup	1	2048	177147	4194304	48828125	362797056	1977326743	8589934592	31381059609	100000000000	285311670611

Music

Template:See also The interval of an octave plus a fourth is an 11th. A complete 11th chord has almost every note of a diatonic scale.

Cultural references

Film

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.

"Eleventh hour"

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

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 Template:Lang Template:Lang, Korean Template:Lang Template:Lang or Template:Lang Template:Lang.

Mysticism

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