I did not know that yesterday!

It is the 50th Post, so in order to celebrate, here is some fact about the number 50, because after all, 50 is a magic number too :o)

In mathematics
Fifty is the smallest number that can be written as the sum of two squares in two distinct ways: 50 = 12 + 72 = 52 + 52. It is also the sum of three squares, 50 = 32 + 42 + 52. It is a Harshad number.

There is no answer to the equation φ(x) = 50, making 50 a nontotient. Nor is there an answer to the equation x - φ(x) = 50, making 50 a noncototient.


In astronomy
Messier object M50, a magnitude 7.0 open cluster in the constellation Monoceros
The New General Catalogue object NGC 50, a spiral galaxy in the constellation Cetus
The Saros number of the solar eclipse series which began on 1201 February 11 BC and ended on 97 April 1. The duration of Saros series 50 was 1298.1 years, and it contained 73 solar eclipses.
The Saros number of the lunar eclipse series which began on -1134 July 3 and ended on 164 August 20. The duration of Saros series 50 was 1298.1 years, and it contained 73 lunar eclipses.
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Other fields
Fifty is also:
The atomic number of tin
The fifth magic number in physics
The traditional number of years in a default jubilee period.
The number of states in the USA (since 1959, still true in 2005).
Hawaii Five-O - TV police show - so-called because Hawaii is the 50th state.
A calibre of ammunition (0.50 inches: see .50 BMG)
In millimeters, the focal length of the normal lens in 35mm photography.
the percentage ( 50% ) equivalent to one half, so that the phrase "fifty-fifty" commonly expresses something divided equally in half, or an event of probability one half
In U.S. dollars, the U.S. fifty dollar bill, the denomination of the Federal Reserve note with Ulysses S. Grant's portrait, the denomination of the savings bond with George Washington's portrait, and the denomination of treasury bonds with Thomas Jefferson's portrait.
In New Zealand, the NZD 50 bill features Sir Apirana Ngata, a prominent Maori politician who worked to protect and rejuvenate Maori culture.
In cents of the U.S. dollar, the denomination of the coin with John F. Kennedy's portrait.
In years of marriage, the gold or "golden" wedding anniversary.
In the title of the movie 50 First Dates, starring Adam Sandler and Drew Barrymore.
part of the name of 50 Cent, a rapper.
One of the years: AD 50, 50 BC, or (for example) 1950.


Other languages
Spanish - Cincuenta
Esperanto - Kvindek
French - Cinquante
Interlingua - cinquanta
Italian - Cinquanta
Netherlands - vijftig
Portuguese - Cinqüenta
Slovenian - število