Kilo-

Kilo- (symbol: k, lowercase) is a unit prefix in the metric system denoting multiplication of the unit by one thousand.

For example:

one kilogram is 1000 grams
one kilometre is 1000 metres
one kilojoule is 1000 joules
one kilobaud is a rate of transfer used primarily in telecommunications
one kilobyte is formally equal to 1000 bytes. However, a second definition and usage has historically been in practice in many fields of computer science and information technology, which defines the prefix kilo when used with byte or bit units of information as 1024 (2¹⁰); this is due to the mathematical coincidence that $2^{10} \approx 10^3.$ Thus, in these fields 1 kilobyte is equal to 1 kibibyte, a new unit standardized as part of the binary prefixes to resolve the ambiguity.^[1]

The kilo prefix is derived from the Greek word χίλιοι (chilioi), meaning thousand. It was originally adopted by Antoine Lavoisier's group in 1795, and introduced into the metric system in France with its establishment in 1799.

Exponentiation

When units occur in exponentiation, such as in square and cubic forms, any multiplier prefix is considered part of the unit, and thus included in the exponentiation.

1 km² means one square kilometre or the area of a square of 1000 m by 1000 m or 10⁶ m².
1 km³ means one cubic kilometre or the volume of a cube of 1000 m by 1000 m by 1000 m or 10⁹ m³.

References

^ Definition of binary prefixes at NIST

SI prefixes
Prefix	Symbol	1000^m	10ⁿ	Decimal	Short scale	Long scale	Scientific notation	Since^{[n 1]}
yotta	Y	1000⁸	10²⁴	1000000000000000000000000	Septillion	Quadrillion	1E24	1991
zetta	Z	1000⁷	10²¹	1000000000000000000000	Sextillion	Trilliard	1E21	1991
exa	E	1000⁶	10¹⁸	1000000000000000000	Quintillion	Trillion	1E18	1975
peta	P	1000⁵	10¹⁵	1000000000000000	Quadrillion	Billiard	1E15	1975
tera	T	1000⁴	10¹²	1000000000000	Trillion	Billion	1E12	1960
giga	G	1000³	10⁹	1000000000	Billion	Milliard	1E9	1960
mega	M	1000²	10⁶	1000000	Million		1E6	1960
kilo	k	1000¹	10³	1000	Thousand		1E3	1795
hecto	h	1000^2/3	10²	100	Hundred		1E2	1795
deca	da	1000^1/3	10¹	10	Ten		1E1	1795
		1000⁰	10⁰	1	One		–	–
deci	d	1000^−1/3	10⁻¹	0.1	Tenth		1E-1	1795
centi	c	1000^−2/3	10⁻²	0.01	Hundredth		1E-2	1795
milli	m	1000⁻¹	10⁻³	0.001	Thousandth		1E-3	1795
micro	μ	1000⁻²	10⁻⁶	0.000001	Millionth		1E-6	1960
nano	n	1000⁻³	10⁻⁹	0.000000001	Billionth	Milliardth	1E-9	1960
pico	p	1000⁻⁴	10⁻¹²	0.000000000001	Trillionth	Billionth	1E-12	1960
femto	f	1000⁻⁵	10⁻¹⁵	0.000000000000001	Quadrillionth	Billiardth	1E-15	1964
atto	a	1000⁻⁶	10⁻¹⁸	0.000000000000000001	Quintillionth	Trillionth	1E-18	1964
zepto	z	1000⁻⁷	10⁻²¹	0.000000000000000000001	Sextillionth	Trilliardth	1E-21	1991
yocto	y	1000⁻⁸	10⁻²⁴	0.000000000000000000000001	Septillionth	Quadrillionth	1E-24	1991
^ The metric system was introduced in 1795 with six prefixes. The other dates relate to recognition by a resolution of the CGPM.

Kilo-

Exponentiation

See also

References