30 (number)
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30 (thirty) is the natural number following 29 and preceding 31.
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| Cardinal | thirty | ||
| Ordinal | thirtieth | ||
| Numeral system | |||
| Factorization | <math>2\cdot 3\cdot 5<math> | ||
| Divisors | 2, 3, 5, 6, 10, 15 | ||
| Roman numeral | XXX | ||
| Binary | 11110 | ||
| Hexadecimal | 1E | ||
| Hebrew | ל (Lamed) | ||
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.
30 is the largest number such that coprimes smaller than itself are also prime. It is a Harshad number.
The Chinese word numeral for thirty is 三十.
A polygon with thirty sides is called a tricontagon. Both an icosahedron and a dodecahedron have 30 edges.
In 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 -2069 October 2 and ended on -572 March 18. 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 -1803 June 19 and ended on -487 August 18. The duration of Saros series 30 was 1316.2 years, and it contained 74 lunar eclipses.
In other fields
Thirty is:
- The atomic number of zinc
- The number of days in the months April, June, September and November.
- 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 of the Thirty Years' War.
- Used to indicate the end of a wire service story.
- 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 E30, the European route from Cork to Samara.
- The number of tracks on The Beatles' eponymous album, usually known as The White Album.
- Part of the name of:
- Thirty odd foot of grunts, the band fronted by actor Russell Crowe
- In the title of the movie 13 Going on 30, starring Jennifer Garner.
- In the title of the Food Network show 30 Minute Meals.
- The number of cars in the Nintendo 64 game F-Zero X.
- Historical years: 30 A.D., 30 B.C., or 1930da:30 (tal)
es:Treinta eo:Tridek fr:30 (nombre) ko:30 ia:30 it:Trenta nl:30 (getal) ja:30 no:30 (tall) pt:Trinta sl:30 (število) sv:30 (tal) zh:30