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10 
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Cardinal 
ten 
Ordinal 
10th
(tenth) 
Numeral system 
decimal 
Factorization 
<math>2\cdot5</math> 
Divisors 
1, 2, 5, 10 
Roman numeral 
X 
Unicode symbol(s) 
X, x 
Greek Prefix 
deca/deka 
Latin Prefix 
deci 
Binary 
1010_{2} 
Octal 
12_{8} 
Duodecimal 
A_{12} 
Hexadecimal 
A_{16} 
 
Chinese numeral 
十，拾 
Hebrew 
י (Yod) 
Khmer 
១០ 
Korean 
십 
Thai 
๑๐ 
10 (ten) is a natural number^{[1]} that follows 9 and precedes 11. It is an integer and a cardinal number, that is, a number that is used for counting.^{[2]} In addition, it is classified as a real number,^{[3]} distinguishing it from imaginary numbers. Ten is the base of the decimal system. It is the total number of digits on a person's two hands or two feet.
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 number of coprimes below it.
Ten is the second discrete biprime (2.5) and the second member of the (2.q) discrete biprime family. Ten has an aliquot sum σ(n) of 8 and is accordingly the first discrete biprime to be in deficit. All subsequent discrete biprimes are in deficit. The aliquot sequence for 10 comprises five members (10,8,7,1,0) with this number being the second composite member of the 7aliquot tree
Ten is a semimeandric number.
Ten is the sum of the first three prime numbers and also of the first four factorials. Ten is the eighth Perrin number, preceded in the sequence by 5, 5, 7.
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 nQueens 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 twodigit 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 
Number 
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 
Ten is a Harshad number in bases 2, 3, 5, 6, 9 and all others above.
List of basic calculations
Multiplication 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 

11 
12 
13 
14 
15 
16 
17 
18 
19 
20 

21 
22 
25 

50 
100 
1000 
<math>10 \times x</math> 
10 
20 
30 
40 
50 
60 
70 
80 
90 
100 

110 
120 
130 
140 
150 
160 
170 
180 
190 
200 

210 
220 
250 

500 
1000 
10000 
Division 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 

11 
12 
13 
14 
15 
<math>10 \div x</math> 
10 
5 
<math>3.\overline{3}</math> 
2.5 
2 
<math>1.\overline{6}</math> 
<math>1.\overline{4}2857\overline{1}</math> 
1.25 
<math>1.\overline{1}</math> 
1 

<math>0.\overline{9}\overline{0}</math> 
<math>0.8\overline{3}</math> 
<math>0.\overline{7}6923\overline{0}</math> 
<math>0.\overline{7}1428\overline{5}</math> 
<math>0.\overline{6}</math> 
<math>x \div 10</math> 
0.1 
0.2 
0.3 
0.4 
0.5 
0.6 
0.7 
0.8 
0.9 
1 

1.1 
1.2 
1.3 
1.4 
1.5 
Exponentiation 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 

11 
12 
13 
<math>10 ^ x\,</math> 
10 
100 
1000 
10000 
100000 
1000000 
10000000 
100000000 
1000000000 
10000000000 

100000000000 
1000000000000 
10000000000000 
<math>x ^ {10}\,</math> 
1 
1024 
59049 
1048576 
9765625 
60466176 
282475249 
1073741824 
3486784401 
10000000000 

25937424601 
61917364224 
137858491849 
In science
Chemistry
Physics
Biology
 Normally, ten is the number of digits a person has on both hands (taken together) or both feet (taken together).
Astronomy
 Ten is the Saros number^{[4]} of the solar eclipse series that began on February 28, 2467 B.C.E. and ended on April 18, 1169 B.C.E. The duration of Saros series 10 was 1298.1 years, and it contained 73 solar eclipses.
 Ten is the Saros number^{[5]} of the lunar eclipse series that began on June 17, 2454 B.C.E. and ended on August 15, 1138 B.C.E. The duration of Saros series 10 was 1316.2 years, and it contained 74 lunar eclipses.
In technology
 Driving a racing car at tentenths is driving as fast as possible, on the limit.
 Tencodes 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.
 Ten is the ASCII and Unicode code point for line feed.
In religion
Judaism
 The Ten Commandments that God gave to Moses (Exodus 20:317 and Deuteronomy 5:721) are considered a cornerstone of Judaism and Christianity.^{[6]}
 In Deuteronomy 26:12, the Torah commands Jews to give onetenth of their produce to the poor (Maaser Ani). From this verse and an earlier verse (Deut. 14:22), there derives a practice for Jews to give onetenth of all earnings to the poor.^{[7]}
 Ten Plagues were inflicted on Egypt (Exodus 712).
 Jews observe the annual Ten Days of Repentance beginning on Rosh Hashanah and ending on Yom Kippur.
 In Jewish liturgy, Ten Martyrs are singled out as a group.
 There are said to be Ten Lost Tribes of Israel (those other than Judah and Benjamin).
 There are Ten Sephirot in the Kabbalistic Tree of Life.
 The Bible records 10 generations between Adam and Noah, and 10 generations between Noah and Abraham.
 In Judaism, ten adults are the required quorum for prayer services.
Christianity
 People traditionally gave onetenth of their produce as tithe. 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.
In music
 The interval of a major or minor tenth is an octave plus a major or minor third.
In sports
 In rugby union, the flyhalf wears the 10 shirt.
 In blackjack, the Ten, Jack, Queen and King are all worth 10 points.
 In tenpin bowling, 10 pins are arranged in a triangular pattern and there are 10 frames per game.
 In football (soccer), 10 is the jersey number of many of the best players, particularly attacking midfielders, especially players from South America. 'Number 10' player is most often used as a synonym for the team's playmaker.
 Ten is the highest score possible in Olympics competitions.
 In cricket, 10 is the number of wickets required to be taken by the bowling side for the batting side to be bowled out.
 In baseball, there are always at least 10 players on the field at a time (including the batter).
Miscellany
10 playing cards of all four suits.
 Increasing a quantity by one order of magnitude means increasing it 10fold. Conversely, decreasing it by an order of magnitude means decreasing it 10fold.
 The term decimate literally means to reduce something by onetenth, although it is also means reducing something drastically.
 A group of ten items or a tenyear time period is called a decade.
 A decapod crustacean has ten limbs.
 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 1to100 scale.
 Someone who scores perfectly is said to have scored "a perfect ten."
 Counting from one to ten before speaking is often done in order to cool one's temper.
 In Chinese astrology, the 10 Heavenly Stems refer to a cyclic number system that is used also for time reckoning.
 The ordinal adjective for ten is denary.
 A 1977 short documentary film Powers of Ten depicts the relative scale of the Universe in factors of ten (orders of magnitude).
 Ten is the number of dots in a tetractys.
See also
Notes
 ↑ A natural number is any number that is a positive integer, such as 1, 2, 3, 4, and so forth. Often, the number 0 is also called a natural number.
 ↑ A cardinal number indicates the quantity of things, but not the order in which they occur. By contrast, ordinal numbers are first, second, third, and so on, indicating their positions in a series.
 ↑ A real number is a number that can be given by a finite or infinite decimal representation. The term "real number" was coined to distinguish it from an "imaginary number." The set of real numbers includes rational and irrational numbers, which can be positive, negative, or zero.
 ↑ Solar Eclipses of Saros 0 to 180 NASA Eclipse Web Site. Retrieved August 20, 2008.
 ↑ Lunar Eclipses of Saros Series 1 to 175 NASA Eclipse Web Site. Retrieved August 20, 2008.
 ↑ Harold Lindsell (ed.), Harper Study Bible: The Holy Bible Revised Standard Version (Grand Rapids, MI: Zondervan Bible Publishers, 1971).
 ↑ Parshas VaYeitzei: Ma'aser Kesafim Retrieved August 22, 2008.
References
 Flegg, Graham. 2002. Numbers: Their History and Meaning. Mineola, NY: Dover Publications. ISBN 0486421651
 Higgins, Peter M. 2008. Number Story: From Counting to Cryptography. London: Copernicus. ISBN 9781848000001
 Ifrah, Georges. 2000. The Universal History of Numbers: From Prehistory to the Invention of the Computer. Translated by David Bellos et al. New York: Wiley. ISBN 0471393401
 McLeish, John. 1994. The Story of Numbers: How Mathematics Has Shaped Civilization. New York: Fawcett Columbine. ISBN 0449909387
 Menninger, Karl. 1992. Number Words and Number Symbols: A Cultural History of Numbers. New York: Dover Publications. ISBN 0486270963
 Wells, D. G. 1998. The Penguin Dictionary of Curious and Interesting Numbers. Rev. ed. London, UK: Penguin Books. ISBN 0140261494
External links
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