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bases

A base-2 number system is called *binary* and a base-10 system
*decimal*, but what how does one term number systems based on 3, 4, 5, 8
or 12 ? This is a question that I had to answer in 1999 March, so I did
some research, and below are (almost all of) my findings. Please inform me of
errors that I have made or of additions that you would like to make via email.

Base | Name |

2 | binary |

3 | ternary [A] |

4 | quaternary |

5 | quinary |

6 | senary |

7 | septenary |

8 | octonary [B] |

9 | nonary |

10 | decimal |

11 | undenary |

12 | duodecimal |

13 | tridecimal |

14 | quattuordecimal |

15 | quindecimal |

16 | sexadecimal [C] |

17 | septendecimal |

18 | octodecimal |

19 | nonadecimal |

20 | vigesimal |

30 | trigesimal |

40 | quadragesimal |

50 | quinquagesimal |

60 | sexagesimal |

70 | septagesimal |

80 | octagesimal |

90 | nonagesimal |

100 | centimal |

200 | bicentimal |

300 | tercentimal |

400 | quattrocentimal |

500 | quincentimal |

[A] | Also “trinary”. |

[B] | Most commonly “octal” but also “octonal” or “octimal”. |

[C] | “hexadecimal” is the common
computer-science terminology, but it is unsatisfactory because it is a
combination of the Greek “hexa” and the Latin “decim”.
The proper Latin should be “sedecim” or “sexdecim”,
yielding either “sedecimal” or “sexadecimal”.
Schwartzman writes: “Since hexadecimal is a rather long word, it is
sometimes abbreviated hex. The word hexadecimal is unusual because
Greek and Latin elements are combined; the expected purely Latin form would be
sexadecimal, but then computer hackers would be tempted to shorten the word to
sex.” [emphasis added] |

Schwartzman S (1994). The Words of Mathematics: an etymological dictionary of mathematical terms used in English (ISBN 0-88385-511-9).