101 (number)

101 (one hundred [and] one) is the

Look up one hundred and one or one hundred one in Wiktionary, the free dictionary.

In mathematics

101 is:

• the 26th prime number and the smallest above 100.
• a palindromic number in decimal, and so a palindromic prime.
• a Chen prime since 103 is also prime, with which it makes a twin prime pair.
• a sexy prime since 107 and 113 are also prime, with which it makes a sexy prime triplet.
• a
  unique prime
  because the period length of its reciprocal is unique among primes.
• an
  real part
  of the form ${\displaystyle 3n-1}$.
• the fifth alternating factorial.^[1]
• a centered decagonal number.^[2]
• the only existing prime with alternating 1s and 0s in decimal and the largest known prime of the form ${\displaystyle 10^{n}+1}$.^[3]
• the number of compositions of 12 into distinct parts.^[4]
• the smallest number that can be expressed as the sum of three distinct nonzero squares in more than two ways: ${\displaystyle 9^{2}+4^{2}+2^{2}}$, ${\displaystyle 8^{2}+6^{2}+1^{2}}$ or ${\displaystyle 7^{2}+6^{2}+4^{2}}$ (see image).^[5][6]

Given 101, the

For a 3-digit number in decimal, this number has a relatively simple divisibility test. The candidate number is split into groups of four, starting with the rightmost four, and added up to produce a 4-digit number. If this 4-digit number is of the form ${\displaystyle 1000a+100b+10a+b}$ (where a and b are integers from 0 to 9), such as 3232 or 9797, or of the form ${\displaystyle 100b+b}$, such as 707 and 808, then the number is divisible by 101.^[9]

On the

• In mineralogy, a Miller index of 101 is a crystal face that crosses the horizontal axis (a) and 3D vertical axis (c) but does not cross the 2D vertical axis (b).
• In physics and chemistry, it is the atomic number of mendelevium, an actinide.
• In astronomy it is the Messier designation given to the Pinwheel Galaxy in Ursa Major.

In books

According to

In American university course numbering systems, the number 101 is often used for an introductory course at a beginner's level in a department's subject area.^[11][12][13] This common numbering system was designed to make transfer between colleges easier. It can also indicate a course for students not intending to major in the subject; e.g. a student intending to major in English would take English 111 not English 101.

In theory, any numbered course in one

Based on this usage, the term "101" (pronounced ONE-oh-ONE) has gained a slang sense referring to basic knowledge of a topic or a collection of introductory materials to a topic, as in the sentence, "Boiling potatoes is Cooking 101".^[13] The Oxford English Dictionary records the usage of "101" in this slang sense from 1986.^[13]

In other fields

In public life:

• In Hinduism, 101 is a lucky number.
• Bill 101, Charter of the French Language in Quebec, Canada.
• 101st kilometre, a condition of release from the Gulag in the Soviet Union.
• 101 is the main Police Emergency Number in Belgium.
• Single Non-Emergency Number (SNEN) in some parts of the UK, a telephone number used to call emergency services that are urgent but not emergencies. 101 is now available across all areas of England and Wales.^[14][15]
• BR-101 and U.S. Route 101
  .
• The number of the first
  checking account
  in the US.
• Lebanese Red Cross EMS Center at Spears is coded 101.

• Taipei 101, the tallest skyscraper in the world from 2004 to 2010.
• An
  HTTP status code
  indicating that the server is switching protocols as requested by the client to do so.
• A term used to define the number of keys on a standard 101 key computer keyboard^[16]
• iCar 101 is a roadable aircraft design concept.^[17][18]
• The
  Zastava 101
  is a compact car by the former Yugoslav automaker.

Proper names:

• Roi Et Province
  , a province in Thailand. The name is literally 101 in Thai language.
• 101 Ranch Oil Company
• "l'ordre des Piliers du 101" is an important student association in Belgium since 1977.

In entertainment:

• 101, a Depeche Mode album
• 101 Dalmatians, a 1956 children's novel by Dodie Smith
• 101 Reykjavík, a 2000 Icelandic film directed by Baltasar Kormákur, 101 being a postcode of Reykjavik
• The apartment number of Neo in The Matrix
• Vault 101 is the starting area of the 2008 action role-playing game Fallout 3
• The Wonderful 101, an action-adventure game for the Wii U
• Produce 101, a Korean reality girl group survival show
• TV show Zoey 101
• The house number of
  Samson en Gert
  in the eponymous Belgian kids' television show.

Others:

• 101 is the identifying number of several infantry units in various militaries across the world, such as the American and Israeli paratrooper brigades.
• 101 was the tail number of a Polish Air Force
  2010 Polish Air Force Tu-154 crash
  .

References

Wikimedia Commons has media related to 101 (number).

• Wells, D.
  ISBN 978-0-14-008029-2