10 Explained

Number:	10
Numeral:	decimal
Divisor:	1, 2, 5, 10
Roman Unicode:	X, x
Greek Prefix:	deca-/deka-
Lang1:	Chinese numeral
Lang1 Symbol:	十，拾
Lang2:	Hebrew
Lang2 Symbol:	י (Yod)
Lang3:	Khmer
Lang3 Symbol:	១០
Lang4:	Armenian
Lang4 Symbol:	Ժ
Lang5:	Tamil
Lang5 Symbol:	௰
Lang6:	Thai
Lang6 Symbol:	๑๐
Lang7:	Devanāgarī
Lang7 Symbol:	१०
Lang8:	Santali
Lang8 Symbol:	᱑᱐
Lang9:	Bengali
Lang9 Symbol:	১০
Lang10:	Arabic & Kurdish & Iranian
Lang10 Symbol:	١٠
Lang11:	Malayalam
Lang11 Symbol:	൰
Lang12:	Egyptian hieroglyph
Lang12 Symbol:
Lang13:	Babylonian numeral

10 (ten) is the even natural number following 9 and preceding 11. Ten is the base of the decimal numeral system, the most common system of denoting numbers in both spoken and written language.

The number "ten" originates from the Proto-Germanic root "*tehun", which in turn comes from the Proto-Indo-European root "*dekm-", meaning "ten". This root is the source of similar words for "ten" in many other Germanic languages, like Dutch, German, and Swedish. The use of the decimal system is probably because humans have ten fingers and ten toes, which people may have used to count by.

Linguistics

A collection of ten items (most often ten years) is called a decade.
The ordinal adjective is decimal; the distributive adjective is denary.
Increasing a quantity by one order of magnitude is most widely understood to mean multiplying the quantity by ten.
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.)

Mathematics

10 is a composite number and a happy number.^[1]
10 is the smallest noncototient number.^[2]

Decagon

See main article: Decagon.

A ten sided polygon is called a decagon.

List of basic calculations

Division	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
10 ÷ x	10	5	3.	2.5	2	1.	1.	1.25	1.	1	0.	0.8	0.	0.	0.
x ÷ 10	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
10	10	100	1000	10000	100000	1000000	10000000	100000000	1000000000	10000000000
x	1	1024	59049	1048576	9765625	60466176	282475249	1073741824	3486784401	10000000000

Science

The metric system is based on the number 10, so converting units is done by adding or removing zeros (e.g. 1 centimetre = 10 millimetres, 1 decimetre = 10 centimetres, 1 meter = 100 centimetres, 1 dekametre = 10 meters, 1 kilometre = 1,000 meters).
The 10th element of the periodic table is neon.
The 10th transition metal is zinc.

Mysticism

In Pythagoreanism, the number 10 played an important role and was symbolized by the tetractys.

Notes and References

Web site: Weisstein . Eric W. . Happy Number . 2025-04-25 . mathworld.wolfram.com . en.
Web site: N. J. A. Sloane. Neil Sloane. A005278: Noncototients. The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. 2016-06-01.