Deca-

Short description: Numerical prefix meaning "ten"

For other uses, see Deca.

Deca (and dec), sometimes deka, is a common English-language numeral prefix derived from the Late Latin decas ("(set of) ten"), from Ancient Greek δεκάς (dekás), from δέκα (déka, "ten"). It is used in many words.

It is also a decimal unit prefix in the International System of Units (SI) denoting a factor of ten, with symbol da and spelled "deca" internationally (or "deka" in American spelling).

SI

The prefix was a part of the original metric system in 1795. It is not in very common usage, although the decapascal is occasionally used by audiologists. The decanewton is also encountered occasionally, probably because it is an SI approximation of the kilogram-force. Its use is more common in Central Europe. In German, Polish, Czech, Slovak, and Hungarian, deka (or deko) is common, and used in self-standing form, always meaning decagram. A runway number typically indicates its magnetic azimuth in decadegrees.

Before the symbol as an SI prefix was standardized as da with the introduction of the International System of Units in 1960, various other symbols were more common, such as dk (e.g., UK and Austria), D (e.g., Germany, Eastern Europe), and Da. For syntactical reasons, the HP 48, 49, 50 series, as well as the HP 39gII and Prime calculators use the unit prefix D.

• 1 decametre = 10 metres
• 1 decalitre = 10 litres
• 1 decare = 10 ares

Examples:

• The blue whale is approximately 30 metres or 3 decametres in length.

As an English prefix

The prefix is used in many words.

General

• Decathlon, a combined event in athletics consisting of ten track and field events.
• Decennial, ten-yearly or a celebration of ten years.

Mathematics

• Decimal based on the number ten.
• Decagon a plane figure with ten sides
• Decahedron a polyhedron with ten faces

Chemistry

• Decane, a hydrocarbon with 10 carbon atoms

Biology

• Decapoda, an order of crustaceans with ten feet

Religion

• The Decalogue, the Ten Commandments

See also

• Metric prefix

External links

• BIPM website

SI prefixes

Prefix		Base 10	Decimal	English word		Adoption
Name	Symbol			Short scale	Long scale
yotta	Y	1024	1000000000000000000000000	septillion	quadrillion	1991
zetta	Z	1021	1000000000000000000000	sextillion	trilliard	1991
exa	E	1018	1000000000000000000	quintillion	trillion	1975
peta	P	1015	1000000000000000	quadrillion	billiard	1975
tera	T	1012	1000000000000	trillion	billion	1960
giga	G	109	1000000000	billion	milliard	1960
mega	M	106	1000000	million		1873
kilo	k	103	1000	thousand		1795
hecto	h	102	100	hundred		1795
deca	da	101	10	ten		1795
		100	1	one		–
deci	d	10−1	0.1	tenth		1795
centi	c	10−2	0.01	hundredth		1795
milli	m	10−3	0.001	thousandth		1795
micro	μ	10−6	0.000001	millionth		1873
nano	n	10−9	0.000000001	billionth	milliardth	1960
pico	p	10−12	0.000000000001	trillionth	billionth	1960
femto	f	10−15	0.000000000000001	quadrillionth	billiardth	1964
atto	a	10−18	0.000000000000000001	quintillionth	trillionth	1964
zepto	z	10−21	0.000000000000000000001	sextillionth	trilliardth	1991
yocto	y	10−24	0.000000000000000000000001	septillionth	quadrillionth	1991