# Re: digits and numbers

From: John Cowan (cowan@locke.ccil.org)
Date: Fri Jun 11 1999 - 13:35:24 EDT

Viranga Ratnaike wrote:

> The simplest thing for me to do is just check the whether the General
> Category is Nd (Number, Decimal Digit).

Yes. The purpose of Nd is to allow you to do arithmetic manipulations;
assuming base-10 numbers, you can assume that (say) 3 consecutive
Nds means 100 * a + 10 * b + c. Other N characters cannot be
assumed to work that way.
>
> What's concerning me is that the codes for the Chinese characters
> (yi, er, san, si, wu, liu, qi, ba, jiu, ling...) are in a character
> range and the General Category for this range is Lo (Letter, Other).

That's because they are the symbols for the *linguistic* forms
(words, zi4) "one", "two", "three" etc.

> The circled ideographs, 3280 to 3289, are classified as numbers "No".
> It seems that they are considered numbers unless they are decomposed.

They are used as symbolic dingbats, not to form numeric strings
like "256" or "3.141592653".

> I noticed that the Hangzhou style numerals (3021 to 3029) were
> classified as Nl (Number, Letter) even tho' they seem to be decimal
> (without the zero but I assume they use DIGIT ZERO). I don't want
> to include Category "Nl" because that would erroneously return true
> for roman numerals.

Hangzhou numerals, IIRC, are typically used in the form
"2 hundred 5 ten 6" for "256", which means they cannot be Nd.

> - what are the Tibetan half digits used for?

"2 5 half-6" means 255.5 (or is it 256.5, I forget).

```--
John Cowan	http://www.ccil.org/~cowan		cowan@ccil.org
You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)
```

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