10

10 (ten) is an even natural number following 9 and preceding 11.

For other uses of the number 10, see 10 (disambiguation).
For other uses of the ordinal 10th, see tenth.

Template:Numbers (10s)
Cardinal	10 ten
Ordinal	10th tenth
Numeral system	decimal
Factorization	$2\cdot 5$
Divisors	1, 2, 5, 10
Roman numeral	X (Unicode: Ⅹ, ⅹ)
prefixes	deca-/deka- (from Greek) deci- (from Latin)
Binary	1010
Hexadecimal	A
Hebrew	י (Yod)

In mathematics

Ten is a composite number, its proper divisors being 1, 2 and 5. Ten is the smallest noncototient, a number that can not be expressed as the difference between any integer and the total of coprimes below it. Ten is a Harshad number and a semi-meandric number.

Ten is the sum of the first three prime numbers and also of the first four factorials. Ten squared equals 100. A polygon with ten sides is a decagon, and 10 is a decagonal number. But it is also a triangular number and a centered triangular number.

Ten is the number of n-Queens Problem solutions for n = 5.

In numeral systems

Ten is the base of the decimal numeral system, by far the most common system of denoting numbers in both spoken and written language. Ten is the first two-digit number in decimal and thus the lowest number where the position of a numeral affects its value. Any integer written in the decimal system can be multiplied by ten by adding a zero to the end (e.g. 855 * 10 = 8550). The reason for the choice of ten is assumed to be that humans have ten fingers (digits).

The digit '1' followed by '0' is how the value of p is written in base p. (E.g. 16 in hexadecimal is 10.)

The Roman numeral for ten is X (which looks like two V's [the Roman numeral for 5] put together); it is thought that the V for five is derived from an open hand (five digits displayed). The Chinese word numeral for ten is 十, which resembles a cross.

Base	Numeral system
1	unary	**********
2	binary	1010
3	ternary	101
4	quaternary	22
5	quinary	20
6	senary	14
7	septenary	13
8	octal	12
9	novenary	11
10	decimal	10
over 10 (e.g., hexadecimal)		A

In science

• The atomic number of neon
• The number of carbon atoms in decane, a hydrocarbon.
• The number of spacetime dimensions in superstring theory.

Astronomy

• Messier object M10, a magnitude 7.5 globular cluster in the constellation Ophiuchus.

• The New General Catalogue object NGC 10, a magnitude 12.5 spiral galaxy in the constellation Sculptor

• The Saros number of the solar eclipse series which began on -2467 February 28 and ended on -1169 April 18. The duration of Saros series 10 was 1298.1 years, and it contained 73 solar eclipses.

• The Saros number of the lunar eclipse series which began on -2454 June 17 and ended on -1138 August 15. The duration of Saros series 10 was 1316.2 years, and it contained 74 lunar eclipses.

In money

• There are ten cents in a U.S. or Canadian dime, itself one tenth of a dollar. The word was shortened from decime.
• The denomination of Canadian paper money bearing a portrait of Sir John A. Macdonald, Canada's first Prime Minister.

In music

• The interval of a major or minor tenth is an octave plus a major or minor third.
• The title of quite a few albums, including recordings by Pearl Jam and LL Cool J. See Ten (album).

In religion

• People traditionally tithed one tenth of their produce. The practice of tithing is still common in Christian churches today, though it is disputed in some circles as to whether or not it is required of Christians.
• The number of Commandments from God to man in Mosaic law. (Exodus 20:2-17, Exodus 34:12-26, and Deuteronomy 5:6-21)
• There are said to be ten "Lost Tribes" of Israel (those other than Judah and Benjamin).
• There are ten sephiroth in the Tree of Life of Jewish mysticism.

In sports

• In chess, each side can promote all eight pawns to have a total of ten bishops, knights, or rooks.
• In rugby union the fly-half wears the 10 shirt.
• In blackjack, the Ten, Jack, Queen and King are all worth 10 points.
• In a bowling alley 10 pins are arranged in a triangular pattern.
• In soccer, the jersey number of many of the best players, especially players from South America. Soccer legend Pelé instilled great prestige in the number in the 1960s and 70s, and perhaps other greats such as Argentina's Diego Maradona and today's Brazilian star Ronaldinho chose the number for that reason. FIFA declined to retire the number at Argentina's request in 2001.

In technology

• Driving a racing car at ten-tenths is driving as fast as possible, on the limit.
• Ten-codes are commonly used on emergency service radio systems.
• Ten refers to the "meter band" on the radio spectrum between 28 and 29.7 MHz, used by amateur radio.
• ASCII and Unicode code point for line feed
• In MIDI, Channel 10 is reserved for unpitched percussion instruments.
• In the Rich Text Format specification, all language codes for regional variants of the Spanish language are congruent to 10 mod 256.
• In Mac OS X, the F10 function key tiles all the windows of the current application and grays the windows of other applications.
• The IP addresses in the range 10.0.0.0/8 (meaning the interval between 10.0.0.0 and 10.255.255.255) is reserved for use by Private networks by RFC 1918.

In other fields

• The number of theatrical Star Trek films that have been released so far.
• A collection of ten items (most often ten years) is called a decade.
• A decapod crustacean has ten limbs.
• To reduce something by one-tenth is to decimate. (In ancient Rome, the killing of one in ten soldiers in a cohort was the punishment for cowardice or mutiny; or, one-tenth of the able-bodied men in a village as a form of retribution, thus causing a labor shortage and threat of starvation in agrarian societies.)
• It takes ten to make a minyan.
• With ten being the base of the decimal system, a scale of 1 to 10 is often used to rank things, as a smaller version of a 1-to-100 scale (as is used in percentages and wine-tasting).
• Blake Edwards' 1979 movie 10.
• Something that scores perfectly is "a perfect ten". A person who is attractive and physically flawless is often said to be "a ten", from the idea of ranking that person's appearance and sex-appeal on a 1-to-10 scale. For example, in the movie 10 Bo Derek is supposedly a "10" on that scale.
• Counting from one to ten before speaking is often done in order to cool one's temper.
• In astrology, Capricorn is the 10th astrological sign of the Zodiac.
• In Chinese astrology, the 10 Heavenly Stems, refer to a cyclic number system that is used also for time reckoning.
• The ordinal adjective is denary.
• An online show hosted by Microsoft [1]
• There is a practical joke where you ask someone to spell: "I-D-ten-T". It comes out looking like the word idiot: ID10T.

Ten is:

• Number of kingdoms in Five Dynasties and Ten Kingdoms Period
• House number of 10 Downing Street
• The number of Provinces in Canada
• The designation of United States Interstate 10, a freeway that runs from California to Florida.
• A Japanese comic: Ten (comic)
• Number of dots in a tetractys.
• Historical years: 10 A.D., 10 B.C., or 1910