# 311 (number)

 ← 310 311 312 →
Cardinal three hundred eleven
Ordinal 311th
(three hundred and eleventh)
Factorization 311
Prime twin prime
Roman numeral CCCXI
Binary 1001101112
Ternary 1021123
Quaternary 103134
Quinary 22215
Senary 12356
Octal 4678
Duodecimal 21B12
Vigesimal FB20
Base 36 8N36
Hebrew שיא

311 is the natural number after 310 and before 312.

## In mathematics

311 is a twin prime with 313; an irregular prime;[1] an Eisenstein prime with no imaginary part and real part of the form ; a Gaussian prime with no imaginary part and real part of the form ; and a permutable prime with 113 and 131.

It can be expressed as a sum of consecutive primes in four different ways: as a sum of three consecutive primes (101 + 103 + 107), as a sum of five consecutive primes (53 + 59 + 61 + 67 + 71), as a sum of seven consecutive primes (31 + 37 + 41 + 43 + 47 + 53 + 59), and as a sum of eleven consecutive primes (11 + 13 + 17 + 19 + 23 + 29 + 31 + 37 + 41 + 43 + 47).

311 is a strictly non-palindromic number, as it is not palindromic in any base between base 2 and base 309.[2]

## Notable uses of numerical value

• 311 is used in the name of a gang in Las Vegas, known as the 311 Boyz.
• 311 was formerly the Los Angeles Police Code for an armed robbery. This is sometimes referenced in Hip-Hop/Rap music and films.
• 3-1-1 is a special phone number used in many large cities such as New York City, Chicago, Houston, and Los Angeles that provides access to non-emergency municipal services.
• 311 is the name of an American alternative rock band.
• As "311" or "3/11", typically pronounced "three-eleven" by analogy with "9/11", it is commonly used to refer the calendar dates November 3 or March 11, depending on which date notation is used. The latter usage may refer to the March 11, 2011, Tōhoku earthquake and tsunami in Japan or the March 11, 2004, Madrid train bombings.
• According to some people 311 stands for KKK because K is the 11th letter of the alphabet (Three 11s = Three Ks = KKK)[3]

## References

1. "Sloane's A000928 : Irregular primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-02.
2. "Sloane's A016038 : Strictly non-palindromic numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-02.
3. Hate Number Symbols: 311 - From A Visual Database of Extremist Symbols, Logos and Tattoos. Anti-Defamation League. Accessed 2008-08-21. "The eleventh letter of the alphabet is the letter "K"; thus 3 times 11 equals "KKK," or Ku Klux Klan."
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