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I thought about the importance of 0 in numeral systems, and base 26 doesn't have one, for example those numbers in base 10 are the same:


In base26, any word would need to be expressed as follow, for example the word


would be equal to


because a is considered to be zero.

Am I right ?

I know the question is not really interesting when thinking about maths, but I just wanted to know where I could be wrong with this.

Also the use of 0 allows to make actual sentences if you use it as a separator.

EDIT: of course when I ask about base 26, it implies letters.

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Hmm, my "base-26" digits go like 0123456789abcdefghijklmnop... –  J. M. Sep 30 '11 at 14:15
Numerals are just symbols. You can declare them as abcdefghijklmnopqrstuvwxyz or you can declare them as 0123456789!@#$%^&*()_+[]{}. Just be sure to give the definition you are using, so other people could follow as well. –  Asaf Karagila Sep 30 '11 at 14:24
Why stop at 27? Go on to ASCII. Or maybe to Unicode. –  GEdgar Sep 30 '11 at 14:28
I don't get your "of course". As already said, it is convention to start using letters only after the traditional digits have been expended... –  J. M. Sep 30 '11 at 15:50
en.wikipedia.org/wiki/Hexavigesimal –  jokoon Sep 30 '11 at 20:10

2 Answers 2

  1. In most place-value systems, including base 26, the convention is to run from 0 through 9 (as J.M. indicates in the comments), and then from A through Z, for as many digits as necessary. Thus:

    • for binary one uses the digits 0 and 1;
    • for duodecimal one uses 09 and A, B;
    • for base 26, one uses 09 and AP;
    • for base 36, one uses 09 and AZ.

    There is no solidly defined convention for bases larger than 36, although I have seen people run through greek letters (which obviously works better if you use lower-case letters, and don't manage to get far enough to encounter omicron or even iota).

  2. In an absolute sense, you are not obligated to use any particular set of symbols at all. Indeed:

    • You can write binary numbers using white and black dots, such as $\bullet$ and $\circ$ , and decide for yourself which stands for zero or one.
    • You can write numbers in duodecimal using the symbols for the zodiacal constellations, setting ♈=0, ♉=1, ♊=2 (naturally), and so on up to ♓=11.
    • You can operate in base 256 using the extended ASCII table, although the non-printable characters may cause you some trouble (and you'll have difficulties expressing decimal points); if you restrict yourself to the printable characters (including the space character), you'll have to be content with base 225.

Number systems are just ways of representing numbers. They are in no sense absolute, but of course when communicating with others it is good to make clear what system you use, or (better still unless you have a good reason) simply adopt a system which is widespread. And if you are interested in the most widespread convention for base 26, it will be starting with 09 as J.M. indicated.

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Agree with all of this, except there is no such thing as "the extended ASCII table", any more than mathematics has, say, a "the meaning of $^*$". –  Henning Makholm Sep 30 '11 at 18:01

@gokoon above actually provides a link that has a thorough discussion of this question: http://en.wikipedia.org/wiki/Hexavigesimal

In short, it is true that in the most common convention, number bases tend to use 0-9A-Z for digits. And the answer above is certainly correct: the symbol choice is entirely arbitrary and has no effect on the calculations. However, in practical terms the question's a little more complex and fairly interesting. Basically, to humans the letters are a convenient and natural way of expressing a 26-based system. Convenience and naturalness are decent enough reasons for choosing a notation! In fact there are three everyday applications that use alphabetic base-26: serial numbers, where base-26 and base-36 are commonly found; slightly modified as the designation system for variable stars; and the 26-adic row and column numbering in Excel and similar spreadsheets.

Now I will admit that these are not deeply theoretical applications. And one must be careful not to carry the symbolism too far and end up in numerology. John Nash was somewhat obsessed by alphabetic base-26 and this was related to his interest in numerology. Nevertheless it's not absurd to look at A-Z for base-26 notation.

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