Metric Numbers

(See also Metric/Imperial Conversion Charts and Unit Converter)

What is kilo, mega, giga, tera ... ?

In the Metric System there are standard ways to talk about big and small numbers:

long rope

Example: A long rope measures one thousand meters

It is easier to say it is 1 kilometer long,

and even easier to write it down as 1 km.

So we used kilo in front of the word meter to make "kilometer".

And the abbreviation is "km" (k for kilo and m for meter, put together).

 

Some more examples:

Example: You put your bag on a set of scales and it shows 2000 grams, we can call that 2 kilograms, or simply 2 kg.

Teaspoonful

Example: Teaspoon

A teaspoon holds 5 thousandths of a liter (51000 of a liter), but it is better to say "5 milliliters", or write it simply as 5 mL.

"kilo", "mega", "milli" etc are called "prefixes":

Prefix: a word part that can be added to the beginning of another word to create a new word

So, using the prefix "milli" in front of "liter" creates a new word "milliliter".

Here we list the prefix for commonly used big and small numbers:

Common Big and Small Numbers

NameThe NumberPrefixSymbol
trillion1,000,000,000,000teraT
billion1,000,000,000gigaG
million1,000,000megaM
thousand1,000kilok
hundred100hectoh
ten10dekada
unit1  
tenth0.1decid
hundredth0.01centic
thousandth0.001millim
millionth0.000 001microµ
billionth0.000 000 001 nanon
trillionth0.000 000 000 001 picop

 

Just remember for large values (each one a thousand times bigger):

"kilo mega giga tera"

and for small values (each one a thousand times smaller):

"milli micro nano pico"

Try To Do Some Yourself!

See the bottom of this page for more questions to challenge yourself ...

How Big Are They?

There is a lot of difference between them. Think in terms of time:

A million seconds is about 12 days
A billion seconds is about 32 years

A longer list:

Much Bigger and Smaller

There are also prefixes for much bigger and smaller numbers:

Some Very Big, and Very Small Numbers

NameThe NumberPrefixSymbol
Very Big !  
septillion1,000,000,000,000,000,000,000,000yottaY
sextillion1,000,000,000,000,000,000,000zettaZ
quintillion1,000,000,000,000,000,000exaE
quadrillion1,000,000,000,000,000petaP
 Very Small !  
quadrillionth0.000 000 000 000 001femtof
quintillionth0.000 000 000 000 000 001attoa
sextillionth0.000 000 000 000 000 000 001zeptoz
septillionth0.000 000 000 000 000 000 000 001yoctoy

 

length continuum thumb Also see
Lengths From Very Small
to Very Large

 

All Big Numbers We Know

NameAs a Power of 10As a Decimal
Thousand1031,000
Million1061,000,000
Billion1091,000,000,000
Trillion10121,000,000,000,000
Quadrillion1015etc ...
Quintillion1018
Sextillion1021
Septillion1024
Octillion1027
Nonillion1030
Decillion1033
Undecillion1036
Duodecillion1039
Tredecillion1042
Quattuordecillion1045
Quindecillion1048
Sexdecillion1051
Septemdecillion1054
Octodecillion1057
Novemdecillion1060
Vigintillion10631 followed by 63 zeros!

 

And a Googol is 1 followed by one hundred zeros (10100) :

10,000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000

Then there is the Googolplex. It is 1 followed by Googol zeros. I can't even write down the number, because there is not enough matter in the universe to form all the zeros:

10,000,000,000,000,000,000,000,000,000,000, ... (Googol number of Zeros)

And a Googolplexian is a 1 followed by Googolplex zeros. Wow.

All Small Numbers We Know

NameAs a Power of 10As a Decimal
thousandths10-30.001
millionths10-60.000 001
billionths10-90.000 000 001
trillionths10-12etc ...
quadrillionths10-15 
quintillionths10-18 
sextillionths10-21 
septillionths10-24 
octillionths10-27 
nonillionths10-30 
decillionths10-33 
undecillionths10-36 
duodecillionths10-39 
tredecillionths10-42 
quattuordecillionths10-45 
quindecillionths10-48 
sexdecillionths10-51 
septemdecillionths10-54 
octodecillionths10-57 
novemdecillionths10-60 
vigintillionths10-63