**Number words**

Words for multiples of thousands.

By a curious historical confusion, two different systems for naming large numbers exist, one in the US and the other in Britain and other parts of the English-speaking world. This could be troublesome, but these days such large numbers are much more often given in unambiguous scientific notation, and the US usage is in any case coming to dominate, as it has almost completely with ** billion**.

The original scheme, invented in France in the sixteenth century, started with ** million** and multiplied 1 by that number the required number of times. The name of the unit was then based on the number of multiplications, using Latin numerals. So a

**was 1 multiplied by a million six times, making a number expressed by 1 followed by 36 zeroes (10**

*sextillion*^{36}in scientific notation). In the eighteenth century French mathematicians changed to multiples of a thousand instead, but took over the existing number names; the Latin numbers then marked one less than the number of multiplications, so that

**was 1 multiplied by a thousand four times. The US system was based on the thousands scheme, but the British stayed with the older millions one.**

*trillion*The following table gives some names and values in the two systems:

Number word |
Millions scheme |
Thousands scheme |

million |
10^{6} |
10^{6} |

(Latin billionbi-, twice) |
10^{12} |
10^{9} |

(Latin trilliontres, three) |
10^{18} |
10^{12} |

(Latin quadrillionquattour, four) |
10^{24} |
10^{15} |

(Latin quintillionquinque, five) |
10^{30} |
10^{18} |

(Latin sextillionsex, six) |
10^{36} |
10^{21} |

(Latin septillionseptem, seven) |
10^{42} |
10^{24} |

(Latin octillionocto, eight) |
10^{48} |
10^{27} |

(Latin nonillionnonus, ninth) |
10^{54} |
10^{30} |

(Latin decilliondecem, ten) |
10^{60} |
10^{33} |

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