# Really Big and Really Small Numbers

There is some international confusion about how to name big numbers. The number $1,000,000$ is one million all over the world. But Americans read $1,000,000,000$ (= ${10}^{9}$ , or a one with nine zeros) as one billion , while in Britain, they say "one thousand million" for ${10}^{9}$ . For the British, "one billion" means ${10}^{12}$ -- what most other people call "one trillion". (These days the British are starting to switch over to the American system, at least in the scientific world.)

Also, in India, after $1,000$ , they start putting commas after every two zeros. In India, $100,000$ is one lakh (our one hundred thousand) and $10,000,000$ is one crore (our ten million).

Below are the standard American and scientific names given to really huge numbers and really tiny numbers. You may want to review your properties of exponents and exponent tables . The prefixes are used in the metric system (for example, $1000$ grams is a kilo gram, and $1,000,000,000$ watts is a giga watt.)

 BIG NUMBERS Number Name Metric Prefix ${10}^{1}=10$ Ten deka- ${10}^{2}=100$ Hundred hecto- ${10}^{3}=1000$ Thousand kilo- ${10}^{4}=10,000$ Ten Thousand myria- ${10}^{6}=1,000,000$ One Million Mega- ${10}^{9}=1,000,000,000$ One Billion Giga- ${10}^{12}$ One Trillion Tera- ${10}^{15}$ One Quadrillion Peta- ${10}^{18}$ One Quintillion Exa- ${10}^{21}$ One Sextillion Zetta- ${10}^{24}$ One Septillion Yotta- ${10}^{27}$ One Octillion ${10}^{30}$ One Nonillion ${10}^{33}$ One Decillion ${10}^{36}$ One Undecillion ${10}^{39}$ One Duodecillion ${10}^{42}$ One Tredecillion ${10}^{45}$ One Quattuordecillion ${10}^{48}$ One Quindecillion ${10}^{51}$ One Sexdecillion ${10}^{54}$ One Septendecillion ${10}^{57}$ One Octodecillion ${10}^{60}$ One Novemdecillion ${10}^{63}$ One Vigintillion ${10}^{100}$ One Googol (named by a nine-year old kid named Milton Sirotta in $1938$ ... but it's in the dictionary! Note that it's spelled differently than that website.) ${10}^{303}$ One Centillion ${10}^{{10}^{100}}$ (that's a $1$ with ${10}^{100}$ zeros!) One Googolplex ("the largest number with a name")

 SMALL NUMBERS Number Name Metric Prefix ${10}^{-1}=0.1$ One Tenth deci- ${10}^{-2}=0.01$ One Hundredth centi- ${10}^{-3}=0.001$ One Thousandth milli- ${10}^{-6}=0.000001$ One Millionth micro- ${10}^{-9}=0.000000001$ One Billionth nano- ${10}^{-12}$ One Trillionth pico- ${10}^{-15}$ One Quadrillionth femto- ${10}^{-18}$ One Quintillionth atto- ${10}^{-21}$ One Sextillionth zepto- ${10}^{-24}$ One Septillionth yocto-