65 (number)
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65 is the natural number following 64 and preceding 66.
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| Cardinal | sixty-five | ||
| Ordinal | 65th (sixty-fifth) | ||
| Factorization | <math>5 \cdot 13<math> | ||
| Roman numeral | LXV | ||
| Binary | 1000001 | ||
| Hexadecimal | 41 | ||
In mathematics
Sixty-five is an octagonal number. It is also a Cullen number. Given 65, the Mertens function returns 0.
This number is the magic constant of 5 by 5 magic square:
<math> \begin{bmatrix}
17 & 24 & 1 & 8 & 15 \\ 23 & 5 & 7 & 14 & 16 \\ 4 & 6 & 13 & 20 & 22 \\ 10 & 12 & 19 & 21 & 3 \\ 11 & 18 & 25 & 2 & 9
\end{bmatrix}. <math>
This number is also the magic constant of n-Queens Problem for n = 5.
65 can be expressed as a sum of two squares in two ways, 65 = 82 + 12 = 72 + 42.
In science
- The atomic number of terbium, a lanthanide
In astronomy,
- Messier object M65, a magnitude 10.5 galaxy in the constellation Leo
- The New General Catalogue object (http://www.ngcic.org/) NGC 65, a spiral galaxy in the constellation Cetus
- The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros1-175.html) of the solar eclipse series which began on -749 April 24 and ended on 513 May 20. The duration of Saros series 65 was 1262.1 years, and it contained 71 solar eclipses.
- The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/LEsaros/LEsaros1-175.html) of the lunar eclipse series which began on -736 August 11 and ended on 797 February 16. The duration of Saros series 65 was 1532.5 years, and it contained 86 lunar eclipses.
In other fields
Sixty-five is also:
- A common speed limit, in miles per hour, for freeways in many U.S. states.
- The designation of Interstate 65, a freeway that runs from Alabama to Indiana.
- The code for international direct dial phone calls to Singapore.
- The standard age for retirement in the UK, Germany and other countries.
- The registry of the U.S. Navy's nuclear aircraft carrier USS Enterprise (CVN-65).
- The year AD 65, 65 BC, or 1965.es:Sesenta y cinco
eo:Sesdek kvin fr:65 (nombre) ko:65 ia:65 it:Sessantacinque ja:65 sl:65 (število) sv:65 (tal) zh:65