Why, in the ASCII extended code, are there characters for one half and one quarter, but not one third?

December 7, 2004 12:30 PM

Why, in the ASCII extended code, are there characters for one half and one quarter, but not one third?
posted by mfbridges to computers & internet (11 comments total)

I'm guessing it's because typewriters typically had characters for 1/2 and 1/4 and not 1/3.

(And no, I don't know why typewriters were like that.)
posted by Vidiot at 12:34 PM on December 7, 2004

you can't represent 1/3 as a (finite) binary fraction, so a computer would never need to display it. 1/2, * and + are sufficient to display all representable binary fractions. i guess the 1/4 is there just to make some representations more compact.
posted by andrew cooke at 12:46 PM on December 7, 2004

er, but a person might want to display 1/3 as a single character.
posted by kenko at 12:50 PM on December 7, 2004

Andrew, I can think of lots of times when a computer would need to display 1/3. There, it just did! Except it used 3 characters instead of one. I guess it's kind of a silly question, maybe its just that 1/4 and 1/2 are used more often?
posted by mfbridges at 12:58 PM on December 7, 2004

It doesn't answer your question at all, but 3/4 would seem pretty important too, if you're going to bother with 1/4 and 1/2.
posted by smackfu at 12:58 PM on December 7, 2004

They didn't have space for three fraction characters so they picked the two they thought would be most common and helpful? At Adobe's site, you can see what they say about fraction characters in their typefaces: "Theses fonts include an expanded set of the most commonly used diagonal fractions beyond 1/4, 1/2 and 3/4 and may include additional fractions such as 1/8, 3/8, 5/8, 7/8, 1/3, and 2/3".

I'd say that 1/3 is just seen as less commonly used than the quarters.
posted by skynxnex at 12:58 PM on December 7, 2004

By the way, i'm asking this because my friend was typing in word, and all his quarters and halves got converted to their single-character equivalents, but the thirds stayed as 3 characters, which is quite annoying.
posted by mfbridges at 1:00 PM on December 7, 2004

Well, he could use the equation editor that's part of word. It should be under there under the insert options.
posted by jasper411 at 1:11 PM on December 7, 2004

The issue in Word isn't really relavant to ASCII extended, since fonts in neither Windows nor Mac use that encoding. For the most part, both OSes use something like Unicode for their fonts. The 1/4, 1/2, and 3/4 characters are in the Latin-1 Supplement to Unicode at points 0BC, 0BD, and 0BE (188, 189, and 190 in decimal).

However, to get 1/3 and other ones, you have to look in Number Forms. 1/3, for example is at hex 2153 (decimal 8531).

If you really want Word to correct 1/3 to ⅓ (which not all fonts have), you can just go into the auto-correct options and add it. Windows has character map which lets you find it easily enough. It's also in Insert/Symbol and then Subset Number Forms (in Word 2002 for Windows at least), or you can do Alt-8531 to insert it or type "2153" in a document then hit Alt-X (although both of those messed up the font for me, just change it back and you're fine).
posted by skynxnex at 1:19 PM on December 7, 2004

Well there's all kinds of characters that aren't there, so it was probably all arguing over the realestate and what characters were more important than others, rather than a statistical analysis of texts.

Besides, it's not like any one should be using extended ascii anymore (as if it ever existed) now that we've got unicode.

mfbridges: See this page on how to insert 1/3 in Windows.
posted by holloway at 1:24 PM on December 7, 2004

Thanks, skynxnex!
posted by mfbridges at 1:24 PM on December 7, 2004