22 (number)

In mathematics

22 is a semiprime, a Smith number, and an Erdős–Woods number. \frac{22}{7} = 3.14{\color{red}28}\ldots is a commonly used approximation of the irrational number , the ratio of the circumference of a circle to its diameter.

22 can read as "two twos", which is the only fixed point of John Conway's look-and-say function.

The number 22 appears prominently within sporadic groups. The Mathieu group M22 is one of 26 sporadic finite simple groups, defined as the 3-transitive permutation representation on 22 points. There are also 22 regular complex apeirohedra.

In other fields

• There are 22 genetically encoded amino acids throughout known life that generate proteins during RNA translation.
• Catch-22 (1961), Joseph Heller's novel, and its 1970 film adaptation gave rise to the expression of logic "catch-22".
• 22 equal temperament is a popular microtonal tuning temperament due to its good approximation of harmonic intervals, especially septimal intervals.

In culture and religion

• 22 is a master number in numerology.
• There are 22 colored properties on a traditional Monopoly board.
• There are 22 cards in the Major Arcana suit of a traditional tarot card deck, though they are often numbered 0-21.

In weights and measures

• The number of yards in a chain.

In other uses

Twenty-two may also refer to:

• In French jargon, "22" is used as a phrase to warn of the coming of the police (typically "22, v'là les flics !", in English: "5-0! Cops!")
• In Spanish lottery and bingo, 22 is nicknamed after its shape.{{Cite news |last1=Cuartas |first1=Javier |title=La suerte de los dos patitos |url=https://elpais.com/diario/1990/01/06/agenda/631580402_850215.html |access-date=17 September 2020 |work=El País |date=1990-01-05 |location=Oviedo |language=es |trans-title=The luck of the two little ducks}}

References

References

1. {{Cite OEIS
2. {{Cite OEIS. A006753. Smith numbers
3. {{Cite OEIS. A059756. Erdős-Woods numbers
4. {{Cite OEIS. A010861. Look-and-say constant sequence 22
5. Weisstein, Eric W.. "Mathieu Groups".
6. Coxeter, H.S.M.. (1991). "Regular Complex Polytopes". Cambridge University Press.
7. (January 2007). "Natural expansion of the genetic code". Nature Chemical Biology.
8. "Definition of CATCH-22".
9. Sharp, Damian. (2001). "Simple Numerology: A Simple Wisdom book (A Simple Wisdom Book series)". Red Wheel.
10. "Definition of CHAIN".
11. (26 April 2010). "Los dos patitos, la niña bonita, la mala pata...".