What Are the Prefixes for SI Units?

In math, you often use prefixes to write large and small numbers in a simpler way. For example, 2 million byte is much easier to write as 2 megabyte or $2$ MB, where M means “mega” and mega $= 1 0^{6} = 1 000 000$ .

Theory

Prefixes


giga	G	billion	$1 0^{9}$

mega	M	million	$1 0^{6}$

kilo	k	thousand	$1 0^{3}$

hecto	h	hundred	$1 0^{2}$

deka	da	ten	$10$

deci	d	one tenth	$1 0^{- 1}$

centi	c	one hundredth	$1 0^{- 2}$

milli	m	one thousandth	$1 0^{- 3}$

micro	μ	one millionth	$1 0^{- 6}$

nano	n	one billionth	$1 0^{- 9}$

Example 1

Uncle Sam bought $2.3$ hectograms (hg) of candy when he was at the store. How many grams does that correspond to?

Hecto (h) means “hundred”. That means Uncle Sam bought

2.3 hg = (2.3 \cdot 100) g = 230 g

of candy.

Example 2

One stage of the cycling race Tour de France can be 192 kilometers (km) long. How many meters is that?

Kilo (k) means “1000”. Thus, the boys ride

192 km = (192 \cdot 1000) m = 192 000 m .

The stage is $192 000$ meters.

Example 3

Albert Einstein was in the laboratory playing with a microscope. While playing, he saw an organism weighing 521 micrograms. How many grams is that?

Micro (μ) means millionth. Thus, the organism weighed

\begin{array}{l} 521 μg & = 521 \cdot \frac{1}{1 000 000} g \\ = 0.000 521 g \end{array}

521 μg = 521 \cdot \frac{1}{1 000 000} g = 0.000 521 g

Note! You switch the prefix with the numeric value of the prefix.

Want to know more?Sign UpIt's free!

What Are the Metric Units for Weight?

How to Find Volumetric Mass Density (Metric)

Go back