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Cardinal | one hundred eleven | |||

Ordinal | 111th (one hundred eleventh) | |||

Factorization | 3 × 37 | |||

Divisors | 1, 3, 37, 111 | |||

Greek numeral | ΡΙΑ´ | |||

Roman numeral | CXI | |||

Binary | 1101111_{2} | |||

Ternary | 11010_{3} | |||

Quaternary | 1233_{4} | |||

Quinary | 421_{5} | |||

Senary | 303_{6} | |||

Octal | 157_{8} | |||

Duodecimal | 93_{12} | |||

Hexadecimal | 6F_{16} | |||

Vigesimal | 5B_{20} | |||

Base 36 | 33_{36} |

**111** (**One hundred [and] eleven**) is the natural number following 110 and preceding 112.

## In mathematics

111 is a perfect totient number.^{[1]}

111 is R_{3} or the second repunit, a number like 11, 111, or 1111 that consists of repeated units, or 1's. It equals 3 × 37, therefore all triplets (numbers like 222 or 777) in base ten are of the form 3*n* × 37. As a repunit, it also follows that 111 is a palindromic number.

All triplets in all bases are multiples of 111 in that base, therefore the number represented by 111 in a particular base is the only triplet that can ever be prime. 111 is not prime in base ten, but is prime in base two, where 111_{2} = 7_{10}. It is also prime in these other bases up to 128: 3, 5, 6, 8, 12, 14, 15, 17, 20, 21, 24, 27, 33, 38, 41, 50, 54, 57, 59, 62, 66, 69, 71, 75, 77, 78, 80, 89, 90, 99, 101, 105, 110, 111, 117, 119 (sequence A002384 in the OEIS)

In base 18, the number 111 is 7^{3} (= 343_{10}) which is the only base where 111 is a perfect power.

The smallest magic square using only 1 and prime numbers has a magic constant of 111:

31 | 73 | 7 |

13 | 37 | 61 |

67 | 1 | 43 |

A six-by-six magic square using the numbers 1 to 36 also has a magic constant of 111:

1 | 11 | 31 | 29 | 19 | 20 |

2 | 22 | 24 | 25 | 8 | 30 |

3 | 33 | 26 | 23 | 17 | 9 |

34 | 27 | 10 | 12 | 21 | 7 |

35 | 14 | 15 | 16 | 18 | 13 |

36 | 4 | 5 | 6 | 28 | 32 |

(The square has this magic constant because 1 + 2 + 3 + ... + 34 + 35 + 36 = 666, and 666 / 6 = 111).

111 is also the magic constant of the n-Queens Problem for n = 6.^{[2]} It is also a nonagonal number.^{[3]}

In base 10, it is a Harshad number.^{[4]}

## Nelson

In cricket, the number 111 is sometimes called "a Nelson" after Admiral Nelson, who allegedly only had "One Eye, One Arm, One Leg" near the end of his life. This is in fact inaccurate - Nelson never lost a leg. Alternate meanings include "One Eye, One Arm, One Ambition" and "One Eye, One Arm, One Arsehole".

It is particularly known as a score in cricket. A score of 111 or multiples thereof (222 = "double nelson", 333 = "triple nelson" and so on) is considered unlucky by some in English cricket. To combat the bad luck those watching are supposed to lift their feet off the ground, famously the international umpire David Shepherd, had a whole retinue of peculiar mannerisms - hops, shuffles, jiggles and so on since an umpire cannot sit down and raise his feet - that he would indulge in if the score was ever a "Nelson" multiple. Particularly if the number of wickets also matched - 111/1, 222/2 etc.

## In other fields

**111** is also:

- The atomic number of the element roentgenium (Rg).
- The chemical compound 1,1,1-Trichloroethane is a chlorinated hydrocarbon that was used as an industrial solvent with a trade name "Solvent 111".
- The emergency telephone number in New Zealand; see 111 (emergency telephone number).
- A non-emergency medical public helpline operating in England and Scotland; see NHS 111.
- It is the lowest positive integer requiring seven syllables to name in English (British and Canadian), or six syllables (by dropping the "and") in American English.
- Occasionally it is referred to as "eleventy-one", as read in The Fellowship of the Ring by J.R.R. Tolkien.
^{[5]} - The first Pacific (4-6-2) locomotive in Great Britain was the Great Western Railway's No. 111 The Great Bear of 1908, designed by George Jackson Churchward. This locomotive was rebuilt into a 4-6-0 Castle Class engine in 1924, renamed Viscount Churchill, and retained the fleet number 111 until scrapped in July 1953.
- In Pakistani history, Pakistan Army's 111 Brigade is notorious for being used for staging the coups to overthrow the elected governments in order to impose martial law.

## See also

## References

**^**Sloane, N. J. A. (ed.). "Sequence A082897 (Perfect totient numbers)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-26.**^**Sloane, N. J. A. (ed.). "Sequence A006003 (a(n) = n*(n^2 + 1)/2)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation.**^**Sloane, N. J. A. (ed.). "Sequence A001106 (9-gonal (or enneagonal or nonagonal) numbers)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-26.**^**Sloane, N. J. A. (ed.). "Sequence A005349 (Niven (or Harshad) numbers)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-26.**^**John Ronald Reuel Tolkien (1993).*The fellowship of the ring: being the first part of The lord of the rings*. HarperCollins. ISBN 978-0-261-10235-4.

- Wells, D.
*The Penguin Dictionary of Curious and Interesting Numbers*London: Penguin Group. (1987): 134

## External links

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