In Australia, trades (like plumbers & carpenters) work in millimetres only.  Well, except for a few old codgers (and a few young
ones) who refuse to stop using inches.

Your 80cm shelf is referred to as eight hundred mm.  The old 6-foot is eighteen hundred, not 180cm or 1.8 metres.  And yes, if you
ask for a 6-foot piece of timber, it will be a bit short!  You need to ask for a piece eighteen thirty in length.

It also sorts out the amatuers from the pro's, if you ask for a 7.5cm pipe in the plumbing shop, you're not a plumber.

Tony


> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf
> Of Gerhard Fiedler
> Sent: Saturday, 8 October 2005 8:46 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Google calculator (includes units)
>
>
> Harold Hallikainen wrote:
>
> > how much do you use centi, deci, deka, etc. instead of just going with
> > milli? In electronics, we don't use centiamps!
>
> I can't really speak for the rest of the world, but I can speak from some
> thirty years experience with everyday life in Germany. The most common
> length units in normal life are centimeter, meter and kilometer.
>
> Millimeter is almost only used in technical contexts; a millimeter is just
> too small for everyday life's issues. For small everyday lengths, the
> centimeter is the unit of choice; you'd say for example "that shelf is
> about two centimeters thick". You probably use centimeter in similar
> contexts as you'd use inch in the USA. Above ten centimeters, you use
> mostly multiples of ten, like in "that cupboard is eighty centimeters wide"
> -- and it's understood that this is not usually 80+-1, it's something
> between roughly 70 and 90 or so. The decimeter is known but I've never seen
> or heard it being used outside of textbooks. Bigger than that, you use
> meters, usually in a form that could be translated as "six meter thirty"
> for 6.3 m. For distances of thousand meters or above, it's the kilometer.
> Dekameter is probably largely unknown to the general public. The 1/2 is
> still common ("three and a half meter") instead of 0.5, but other than
> that, it's mostly decimal if you need to go to precisions higher than 1/2.
> Rounding happens more in the numbers than in jumping units; you'd say that
> your street block is 80 meters wide, or that it's only 300 meters to your
> friend's house.
>
> You are right for technical drawings -- here the normal micro, milli, kilo
> are being used almost exclusively.
>
> I've heard on occasion the argument that in the metric system the numbers
> are not round. That's just plain hogwash. Of course, if you want to express
> 3 1/2 inches in millimeters and calculate the /exact/ value of 3 1/2
> inches, it's something that has usually one decimal of a millimeter -- not
> really a "round" number (88.9 mm). But if you consider that the 3 1/2
> inches are in reality 3 1/2 inches +-1/4 inch, for example, then you surely
> can find a centimeter value within that range that is as "round" as "3 1/2"
> -- try nine, which is what you probably would come up with if you started
> out estimating in centimeters. And there's not much difference whether you
> call that log a two by four or a five by ten; it's neither 2 by 4 inches
> nor 5 by 10 centimeters anyway :)
>
> Gerhard
> --
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