Kilo

From Wikipedia, the free encyclopedia

Kilo is also the letter K in the NATO phonetic alphabet.

Kilo class is a type of naval submarine made in Russia.

kilo- (symbol: k) is a prefix in the SI and other systems of units denoting 10³ or 1000. For example:

• kilogram is 1000 grams
• kilometre is 1000 metres
• kilowatt is 1000 watts
• kilojoule is 1000 joules

Officially adopted in 1795 (though in common use before that), it comes from the Greek χίλιοι ("khilioi"), meaning thousand.

"Kilo" is often used by itself as an abbreviation for "kilogram". Also, technical people often use the term "k", pronounced like the letter, to refer to a thousand of something, especially units of money or population. On the other hand, the kilometre is sometimes informally abbreviated to "k"; in this context it is widely used in the United States in reference to running races (for example, a "10k"). "Click" or "klick" can also be heard in informal usage, especially in the U.S. military.

SI prefixes

1000n	10n	Prefix	Symbol	Short scale	Long scale	Decimal equivalent in SI writing style
10008	1024	yotta	Y	Septillion	Quadrillion	1 000 000 000 000 000 000 000 000
10007	1021	zetta	Z	Sextillion	Trilliard (thousand trillion)	1 000 000 000 000 000 000 000
10006	1018	exa	E	Quintillion	Trillion	1 000 000 000 000 000 000
10005	1015	peta	P	Quadrillion	Billiard (thousand billion)	1 000 000 000 000 000
10004	1012	tera	T	Trillion	Billion	1 000 000 000 000
10003	109	giga	G	Billion	Milliard (thousand million)	1 000 000 000
10002	106	mega	M	Million		1 000 000
10001	103	kilo	k	Thousand		1 000
10002/3	102	hecto	h	Hundred		100
10001/3	101	deca, deka	da	Ten		10
10000	100	(none)	(none)	One		1
1000−1/3	10−1	deci	d	Tenth		0.1
1000−2/3	10−2	centi	c	Hundredth		0.01
1000−1	10−3	milli	m	Thousandth		0.001
1000−2	10−6	micro	µ (u)	Millionth		0.000 001
1000−3	10−9	nano	n	Billionth	Milliardth	0.000 000 001
1000−4	10−12	pico	p	Trillionth	Billionth	0.000 000 000 001
1000−5	10−15	femto	f	Quadrillionth	Billiardth	0.000 000 000 000 001
1000−6	10−18	atto	a	Quintillionth	Trillionth	0.000 000 000 000 000 001
1000−7	10−21	zepto	z	Sextillionth	Trilliardth	0.000 000 000 000 000 000 001
1000−8	10−24	yocto	y	Septillionth	Quadrillionth	0.000 000 000 000 000 000 000 001

[edit] Use in computing

In computing, kilo does not always denote 1000 but is sometimes equal to 1024 (2¹⁰), most often when discussing storage. For example, a kilobyte is frequently 1024 bytes, and not 1000 bytes. A common convention is to use k for 1000 and K for 1024, but this is not universally recognized and cannot be relied upon or extended to the higher prefixes. The binary prefix kibi- (symbol Ki) for 1024 has since been introduced to dispel the ambiguity, but has not gained much popularity yet.

Hard disk manufacturers use the normal decimal prefixes listed above instead of the binary prefixes that are customary in computer memory, which some claim is an intentionally misleading overstatement of capacity. This effect is stronger as the capacity grows. In the case of a kilobyte the difference is only 2.4%, but for a terabyte the difference is about 10%.

See Binary prefix for more details.