Military Time, Spoken

Date: 10/18/2002 at 04:43:57
From: Syarifah Liyana Syed Sadair
Subject: 24-hour clock system

I need to know the correct way of saying the 24-hour clock system.  
For example: Is 1900 read as "nineteen hundred hours" or "nineteen 
hours"? How do you read 0035, or 1325, or 1505? 

Please also tell me how to write them. Is it written with a colon, 
23:45, 1534, or 20.05?

Date: 10/18/2002 at 13:42:11
From: Doctor Peterson
Subject: Re: 24-hour clock system

Hi, Syarifah.

This is a good question without a single good answer.

In the United States, this is commonly referred to as "military time," 
because it is used primarily by the military and by groups influenced 
by the military (aircraft, radio). They traditionally drop the colon 
and read the number as if it were a single number, so that 1900 is 
read "nineteen hundred" rather than "19 o'clock" or "19 hours." (It 
would be wrong to say "1900 hours," but that doesn't mean people don't 
commonly, or even usually, say it that way). They also tend to read 
0530 as "oh-five-thirty" (or, if they are more conscientious, as 
"zero-five-thirty"). Similarly, 1325 is "thirteen twenty-five."

You can read about this military version of 24-hour time here:

   Military Time - U.S. Coast Guard
   http://www.uscg.mil/reserve/pubs/helmsman/time.htm 

    Time is told on a continuous 24 hour clock. Rather than
    distinguishing between morning (AM) and afternoon (PM), the
    time is read sequentially from 0001 to 2400. For example,
    fifteen minutes past midnight is written as 0015 and spoken
    as "zero, zero, fifteen." One thirty in the morning is
    written s 0130 and spoken as "zero, one, thirty."  Two
    o'clock in the afternoon is two hours after twelve and
    therefore is written as 1400 and spoken as "fourteen
    hundred." Quarter to ten in the evening is written as 2145
    and spoken as "twenty-one, forty-five."

See also

   Military Time - Dr. Math archives
   http://mathforum.org/library/drmath/view/58434.html 

    Military Time / The "24-Hour" Clock - GMRS
   http://www.g-m-r-s.org/military-time.htm 

But 24-hour time is not used only in the military, and not all users 
read it and write it this way. I do not know all cultures in which 
some form of 24-hour time is used, but my understanding is that the 
non-military form (commonly used in Europe, for instance), 

    - is written WITH the colon (as "13:25"; or, in at least some
      European countries, with a period, as in "13.25")

    - starts at 0:00 rather than ending with 24:00

    - is read as "13 o'clock" or "thirteen twenty-five" (in English,
      or the equivalent in other languages) the same as 12-hour time.

If you have any further questions, feel free to write back.

- Doctor Peterson, The Math Forum
  http://mathforum.org/dr.math/ 

Date: 10/20/2002 at 19:32:19
From: Syarifah Liyana Syed Sadair
Subject: Thank you (24-hour clock system)

Thank you so much for answering my question about the 24-hour clock 
system. It has been much of a help. I really need to know how to read 
the 24-hour clock system correctly because I am working with the 
Ministry of Education of Malaysia and we are putting it in the 
Mathematics curriculum.

How do you think the British read it? Some people say that 1900 cannot 
be read as "nineteen hundred hours" because the 00 does not stand for 
"hundred". It is "nineteen hours" and "zero minutes".

Date: 10/20/2002 at 22:16:18
From: Doctor Peterson
Subject: Re: 24-hour clock system

Hi, Syarifah.

Yes, the "hundred" is used only in the military version, and is not 
to be recommended! I assume the British version would be "19 o'clock," 
but I am not sure. I would recommend looking to some British 
curriculum for a check.

- Doctor Peterson, The Math Forum
  http://mathforum.org/dr.math/