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Re: Scientific Number Format

From: Bert Bos <Bert.Bos@sophia.inria.fr>
Date: Wed, 2 Sep 1998 17:34:38 +0200 (MET DST)
To: pwatson@mail.com
Cc: www-international@w3.org
Message-ID: <13805.2829.717705.465795@www43.inria.fr>
Paul Watson writes:
 > It is well known that locales vary in how numbers are formatted.
 >    en_US   123.45
 >    fr_FR   123,45
 > Does this extend to the technical and scientific community? Would
 > the French user of a device prefer to see 5,5 or 5.5 when representing
 > volts or degrees centigrade?

Depends on the context: in an English sentence, use a dot, in French
(or Dutch, German,...) use a comma.

But the best is to avoid ambiguity:

  - avoid three digits after the decimal point, either use 2 or 4
  - include both a thousands separator and a decimal point
  - write the number in words
  - (in some languages) put the unit before the fraction: 45F25
  - provide redundancy in some other way, e.g., by setting
    expectations about the possible range, or relating the number to
    something well-known ("about the weight of a small dog, or

 > A quick survey of web sites in the .fr domain shows both
 > representations are used. What is the best use for the French
 > customer.
 > Also, do technical and scientific users want to see thousand
 > separators?

I prefer a half-space between the thousands. That way I can't be
confused by the difference between commas and periods, and I find it
even easier to read than the dot (even though I learned the dot in

In ASCII, where there is no half-space, I try to avoid thousands:
instead of "2,613,245 bytes," I write "about 2.5 Mb"

In fact, I don't come across many situation that need more than 2
digits, but if thousands separators are unavoidable, try to include
*two* of them (i.e., try to make it a million). That avoids mistaking
them for decimal points.

If you know your audience is technical, you can also use the exponent
notation: 2.5E+6. (In print, that would be 2.5*10^6, of course.) Even
if you mistype the dot as a comma, people are unlikely to misread it,
since thousands should not occur in this notation.

  Bert Bos                                ( W 3 C ) http://www.w3.org/
  http://www.w3.org/people/bos/                              W3C/INRIA
  bert@w3.org                             2004 Rt des Lucioles / BP 93
  +33 (0)4 92 38 76 92            06902 Sophia Antipolis Cedex, France
Received on Wednesday, 2 September 1998 11:34:48 UTC

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