Exa

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For the X Window System acceleration architecture, see EXA.

exa- (symbol E) is a prefix in the SI system of units denoting 10¹⁸ or 1 000 000 000 000 000 000.

Adopted in 1991, it comes from the Greek ἕξ, meaning six (like hexa-), because it is equal to 1000⁶.

Example:

• 1 EeV = 10¹⁸ electronvolts = 0.1602 joule

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] See also

• SI prefix
• Binary prefix

[edit] External link

• BIPM website