# 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:

- "kilo" for a thousand,
- "mega" for a million,
- and more ...

### Example: A long rope measures **one thousand** meters

It is easier to say it is 1 **kilo**meter long,

and even easier to write it down as **1 km**.

So we used ** kilo** in front of the word

**to make**

*meter**"*.

**kilometer**"And the abbreviation is "* km*" (

*for kilo and*

**k***for meter, put together).*

**m**

### 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.

### Example: Teaspoon

A teaspoon holds 5 **thousandths** of a liter (\frac{5}{1000} of a liter), but it is better to say "5 **milli**liters", 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

Name | The Number | Prefix | Symbol |

trillion | 1,000,000,000,000 | tera | T |

billion | 1,000,000,000 | giga | G |

million | 1,000,000 | mega | M |

thousand | 1,000 | kilo | k |

hundred | 100 | hecto | h |

ten | 10 | deka | da |

unit | 1 | ||

tenth | 0.1 | deci | d |

hundredth | 0.01 | centi | c |

thousandth | 0.001 | milli | m |

millionth | 0.000 001 | micro | µ |

billionth | 0.000 000 001 | nano | n |

trillionth | 0.000 000 000 001 | pico | p |

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!

- How do you refer to a million liters?
- How about one
**billionth**of a meter?

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:

**12 days**

A billion seconds is about

**32 years**

A longer list:

- A
**thousand**seconds is about a**quarter of an hour** - A
**million**seconds is about**12 days** - A
**billion**seconds is about 32 years, almost**half a lifetime** - A
**trillion**seconds is about 32,000 years (the last Ice Age finished 12,000 years ago)

## Much Bigger and Smaller

There are also prefixes for much bigger and smaller numbers:

## Some Very Big, and Very Small Numbers

Name | The Number | Prefix | Symbol |

Very Big ! | |||

septillion | 1,000,000,000,000,000,000,000,000 | yotta | Y |

sextillion | 1,000,000,000,000,000,000,000 | zetta | Z |

quintillion | 1,000,000,000,000,000,000 | exa | E |

quadrillion | 1,000,000,000,000,000 | peta | P |

Very Small ! | |||

quadrillionth | 0.000 000 000 000 001 | femto | f |

quintillionth | 0.000 000 000 000 000 001 | atto | a |

sextillionth | 0.000 000 000 000 000 000 001 | zepto | z |

septillionth | 0.000 000 000 000 000 000 000 001 | yocto | y |

Also see Lengths From Very Small to Very Large |

## All Big Numbers We Know

Name | As a Power of 10 | As a Decimal |

Thousand | 10^{3} | 1,000 |

Million | 10^{6} | 1,000,000 |

Billion | 10^{9} | 1,000,000,000 |

Trillion | 10^{12} | 1,000,000,000,000 |

Quadrillion | 10^{15} | etc ... |

Quintillion | 10^{18} | |

Sextillion | 10^{21} | |

Septillion | 10^{24} | |

Octillion | 10^{27} | |

Nonillion | 10^{30} | |

Decillion | 10^{33} | |

Undecillion | 10^{36} | |

Duodecillion | 10^{39} | |

Tredecillion | 10^{42} | |

Quattuordecillion | 10^{45} | |

Quindecillion | 10^{48} | |

Sexdecillion | 10^{51} | |

Septemdecillion | 10^{54} | |

Octodecillion | 10^{57} | |

Novemdecillion | 10^{60} | |

Vigintillion | 10^{63} | 1 followed by 63 zeros! |

And a **Googol** is 1 followed by one hundred zeros (10^{100}) :

*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

Name | As a Power of 10 | As a Decimal |

thousandths | 10^{-3} | 0.001 |

millionths | 10^{-6} | 0.000 001 |

billionths | 10^{-9} | 0.000 000 001 |

trillionths | 10^{-12} | etc ... |

quadrillionths | 10^{-15} | |

quintillionths | 10^{-18} | |

sextillionths | 10^{-21} | |

septillionths | 10^{-24} | |

octillionths | 10^{-27} | |

nonillionths | 10^{-30} | |

decillionths | 10^{-33} | |

undecillionths | 10^{-36} | |

duodecillionths | 10^{-39} | |

tredecillionths | 10^{-42} | |

quattuordecillionths | 10^{-45} | |

quindecillionths | 10^{-48} | |

sexdecillionths | 10^{-51} | |

septemdecillionths | 10^{-54} | |

octodecillionths | 10^{-57} | |

novemdecillionths | 10^{-60} | |

vigintillionths | 10^{-63} |