78 (number)
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78 (seventy-eight) is the natural number following 77 and followed by 79.
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| Cardinal | seventy-eight | ||
| Ordinal | 78th (seventy-eighth) | ||
| Factorization | <math>2 \cdot 3 \cdot 13<math> | ||
| Divisors | 2, 3, 6, 13, 26, 39 | ||
| Roman numeral | LXXVIII | ||
| Binary | 1001110 | ||
| Hexadecimal | 4E | ||
In mathematics
78 is a triangular number, and its factorization makes it a sphenic number.
Karl A. Dahlke proved in 1989 that 78 heptominos of this shape ( Missing image
Heptomino-78.png
image:heptomino-78.png
), at a minimum, are required to fill a rectangle.
In science
- The atomic number of platinum
In astronomy,
- Messier object M78, a magnitude 8.0 diffuse nebula in the constellation Orion
- The New General Catalogue object (http://www.ngcic.org/) NGC 78, a magnitude 12.8 barred spiral galaxy in the constellation Pisces
- The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros1-175.html) of the solar eclipse series which began on -463 June 9 and ended on 817 July 18. The duration of Saros series 78 was 1280.1 years, and it contained 72 solar eclipses.
- The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/LEsaros/LEsaros1-175.html) of the lunar eclipse series which began on -125 April 10 and ended on 1155 May 18. The duration of Saros series 78 was 1280.1 years, and it contained 72 lunar eclipses.
In other fields
78 is also:
- The designation of Interstate 78, a freeway that runs from Pennsylvania to New York.
- In reference to gramophone records, 78 refers those meant to be spun at 78 revolutions per minute. Compare: LP, 33 and 45.
- A standard Tarot deck containing the 22 cards of the major arcana (including the fool) and the 56 cards of the minor arcana make up 78 cards.
- The total number of gifts in the song The Twelve Days of Christmas (since 78 is the 12th triangular number).
- The year AD 78, 78 BC, or 1978.es:Setenta y ocho
eo:Sepdek ok ko:78 ia:78 it:Settantotto ja:78 sl:78 (število) sv:78 (tal) zh:78