Prefix Symbol Exponential Word Number (multiply by)
yocto y 10-24 septillionth 0.000 000 000 000 000 000 000 001
zepto z 10-21 sextillionth 0.000 000 000 000 000 000 001
atto a 10-18 quintillionth 0.000 000 000 000 000 001
femto f 10-15 quadrillionth 0.000 000 000 000 001
pico- p 10-12 trillionth 0.000 000 000 001
nano- n 10-9 billionth 0.000 000 001
micro- μ 10-6 millionth 0.000 001
milli- m 10-3 thousandth 0.001
centi- c 10-2 hundredth 0.01
deci- d 10-1 tenth 0.1
0
deca- d 10 ten 10
hecto- h 102 hundred 100
kilo- k 103 thousand 1000
mega- M 106 million 1,000,000
giga- G 109 billion 1,000,000,000
tera- T 1012 trillion 1,000,000,000,000
peta- P 1015 quadrillion 1,000,000,000,000,000
exa- E 1018 quintillion 1,000,000,000,000,000,000
zetta Z 1021 sextillion 1,000,000,000,000,000,000,000
yotta Y 1024 septillion 1,000,000,000,000,000,000,000,000
Some comparisons . . .
A meter is about the length of a person's arm.
A nanometer is one billionth of a meter. Think of it this way: There are as many nanometers in an inch as there are inches in 400 miles.
An ant's eye is about 50 micrometers.
The dime is about 1 millimeter thick. (A millimeter is one million times larger than a nanometer!)
A centimeter is about the width of a popsicle stick.
Mega comes from the Greek megasmeaning "great, large, or mighty."
Giga is from the Greek gigas meaning "giant."
Kilo comes from the Greek khilioimeaning 1,000.
The Earth has a mass of approximately 6000 Yottagrams!
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The basic metric prefixes are: kilo (k), hecto (h), deca (da), unit (base unit), deci (d), centi (c), and milli (m). These prefixes represent powers of 10, with kilo representing 10^3, hecto representing 10^2, deca representing 10^1, and so on. They are used to indicate decimal multiples or fractions of the base unit.
In decreasing order:
x 1024 = Y = yotta-
x 1021 = Z = zetta-
x 1018 = E = exa-
x 1015 = P = peta-
x 1012 = T = tera-
x 109 = G = giga-
x 106 = M = mega-
x 103 = k = kilo
x 102 = h = hecto-
x 10 = da = deca-
x 1 = <none> = <none> - the unit itself
x 10-1 = d = deci-
x 10-2 = c = centi-
x 10-3 = m = milli-
x 10-6 = μ = micro-
x 10-9 = n = nano-
x 10-12 = p = pico-
x 10-15 = f = femto-
x 10-18 = a = atto-
x 10-21 = z = zepto-
x 10-24 = y = yocto-
There are twenty prefixes in the SI system, ten representing multiples and ten representing fractions of the base unit.
Using metres as an example.
kilo- 1 kilometre= 1 x 103 metres, 1 000 m.
mega= 1 Mm= 1 x 106m 1 000 000 m
giga- 1 Gm=1 x 109m, 1 000 000 000 m.
tera-, 1Tm= 1 x 1012m 1 000 000 000 000 m
peta- 1 Pm= 1 x 1015m, 1 000 000 000 000 000 m.
exa, 1 Em= 1 x 1018m, 1 000 000 000 000 000 000 m.
zetta- 1 Zm= 1 x 1021m, 1 000 000 000 000 000 000 000 m.
yotta- 1 Ym= 1 x 1024m, 1 000 000 000 000 000 000 000 000 m.
There are also deca and hecto fro tens and hundreds, but these a never used.
milli- 1 mm = 1 x 10-3m, 0.001 m
micro- 1μm= 1 x 10-6m, 0.000 001 m
nano- 1 nm= 1 x 10-9m, 0.000 000 001m
pico, 1 pm= 1 x 10-12m, 0.000 000 000 001 m
femto- 1 fm= 1 x 10-15m, 0.000 000 000 000 001 m
atto- 1 am = 1 x 10-18m, 0.000 000 000 000 000 001 m
zepto- 1 zm= 1 x 10-21m, 0.000 000 000 000 000 000 001 m
yocto- 1 ym= 1 x 10-24m, 0.000 000 000 000 000 000 000 001 m
There are also deci and centi for tenths and hundredths but these are rarely if ever used.
Prefixes for multiples are upper case symbols, except for kilo,k. Prefixes for fractions are lowercase symbols.
The largest metric prefixes are yotta- (Y) and zetta- (Z), representing 10^24 and 10^21, respectively. These prefixes are used to describe extremely large quantities, such as data storage capacities or distances in space.
The prefixes for deca indicate a factor of ten. For example, "deca-" represents 10, "hecto-" represents 100, and "kilo-" represents 1,000. These prefixes are commonly used in the metric system for units of measurement.
A helpful acronym to remember the prefixes in the metric system is "King Henry Died By Drinking Chocolate Milk," representing kilo, hecto, deca, base unit (gram, liter, meter), deci, centi, milli in increasing order of magnitude. This can assist in recalling the meaning and order of the prefixes.
The metric prefix deci- represents a factor of 0.1, which means one-tenth or 1/10 of the base unit. It is often used in the metric system to denote a fraction of a unit.
The basic prefixes deci, centi and milli decrease by powers of ten and deca, hecto and kilo increase by powers of ten.