30_(NUMBER)

(Redirected from Thirty)
'30' ('thirty') is the natural number following 29 and preceding 31.
Cardinal 30
thirty
Ordinal 30th
thirtieth
Numeral system trigesimal
Factorization 2cdot 3cdot 5
Divisors 1, 2, 3, 5, 6, 10, 15, 30
Roman numeral XXX
Roman numeral (Unicode) XXX, xxx
Binary 11110
Octal 36
Duodecimal 26
Hexadecimal 1E
Hebrew ל (Lamed)


Contents
In mathematics
In science
Astronomy
In other fields
Historical years
In sports
Music
References

In mathematics


It is a primorial as well as the sum of the squares of the integers 1, 2, 3 and 4. It is the first sphenic number and the first Giuga number. It is the sum of the first four squares, which makes it a square pyramidal number. Adding up some subsets of its divisors (e.g., 5, 10 and 15) gives 30, hence 30 is a semiperfect number.
30 is the largest number such that coprimes smaller than itself are also prime.[1]
A polygon with thirty sides is called a tricontagon. Both an icosahedron and a dodecahedron have 30 edges.
''E''8 has Coxeter number 30.
30 is a Harshad number.

In science



★ The atomic number of zinc
Astronomy


Messier object M30, a magnitude 8.5 globular cluster in the constellation Pegasus

★ The New General Catalogue object NGC 30, a double star in the constellation Pegasus

★ The Saros number of the solar eclipse series which began on October 2, 2069 BC and ended on March 18, 572 BC. The duration of Saros series 30 was 1496.5 years, and it contained 84 solar eclipses. Further, the Saros number of the lunar eclipse series which began on June 19 1803 BC and ended on August 18 487 BC. The duration of Saros series 30 was 1316.2 years, and it contained 74 lunar eclipses.

In other fields


'Thirty' is:

★ The number of days in the months April, June, September and November (and in unusual circumstances February - see February 30)

★ The total number of major and minor keys in Western tonal music, including enharmonic equivalents

★ In years of marriage, the pearl wedding anniversary

★ The duration in years of the Thirty Years' War

★ Used to indicate the end of a wire service story. (Possibly a corruption of German ''fertig'' - "finished, ready" - or in journalistic context "end of story"); in several Superman stories from various titles, failure by a Daily Planet employee to use this signature proved to be a plot point revealing a character's impersonation, mind control, etc.

★ The code for international direct dial phone calls to Greece

★ The house number of 30 St Mary Axe (The Gherkin)

★ The designation of Interstate 30, a freeway that runs from Texas to Arkansas

★ The designation of U.S. Route 30, a highway that runs from Oregon to New Jersey

★ Various other routes have been numbered "30"; for example, New York State Route 30 which runs from the Pennsylvania border to the Canadian border

★ The designation of E30, the European route from Cork to Samara

★ The number of tracks on The Beatles' eponymous album, usually known as ''The White Album''

★ The number of cars in the Nintendo 64 game F-Zero X

★ ''-30-'', a motion picture about work in a Los Angeles newspaper, starring Jack Webb and William Conrad

★ A stage in young adulthood

★ Part of the name of:


★ ''Thirty odd foot of grunts'', the band fronted by actor Russell Crowe


★ The movie title ''13 Going on 30'', starring Jennifer Garner


★ The title of the Food Network show ''30 Minute Meals''

★ The uniform number of Maury Wills when he played for the Los Angeles Dodgers.

Judas Iscariot betrayed Jesus for 30 pieces of silver. Matthew 26:15.

Historical years


'30 A.D.', 30 B.C., 1930, 2030, etc.

In sports



★ In tennis, the number 30 represents the second point gained in a game.

★ In hockey, All-Star goaltenders Ryan Miller of the Buffalo Sabres and Martin Brodeur of the New Jersey Devils wear the number 30

Music



★ ''30'', album from 2001 by Harry Connick, Jr.

30 Seconds to Mars

References


1. Michael Slone, Every positive integer greater than 30 has at least one composite totative from PlanetMath. Accessed 24 April 2007


Prime Curios! 30 from the Prime Pages

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