10

This article is about the number. For the years, see 10 BC and AD 10. For other uses, see Ten (disambiguation).

"10th" redirects here. For other uses, see Tenth (disambiguation).

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.

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

Ten is the smallest noncototient number. There are exactly 10 small Pisot numbers that do not exceed the golden ratio.

Decagon

Main article: Decagon

A ten sided polygon is called a decagon.

List of basic calculations

Multiplication	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	20	25	50	100	1000
10 × x	10	20	30	40	50	60	70	80	90	100	110	120	130	140	150	160	200	250	500	1000	10000

Division	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
10 ÷ x	10	5	3.3	2.5	2	1.6	1.428571	1.25	1.1	1	0.90	0.83	0.769230	0.714285	0.6
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
10x	10	100	1000	10000	100000	1000000	10000000	100000000	1000000000	10000000000
x10	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).

Mysticism

The tetractys

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

See also

• Mathematics portal
• List of highways numbered 10