I’ve learned about them in school, but I’ve never heard anyone say something is 8 decameters long or anything like that. I’m an American.
Saying something is 80 meters long is far easier to process than eight decameters.
These two specifically - I don’t think I’ve ever seen them.
Hectoliters are sometimes used e.g. for measuring beer consumption for an event, decimeters in some informal contexts, some country commonly describe drink sizes in centiliters or deciliters.
Centimeters are common, I’d say more common than millimeters in informal context.
From my experience in Norway, these are typical in context of daily speech:
Weight (gram): tonne (a substitute name for Mg (Mega)), kg, hg, g, mg, μg (mostly in medicine)
Distance (meter): mil (10 km), km, m, dm (kinda rare), cm, mm
Volume (liter): l, dl, cl, ml
In my experience, the deca-predix is very rarely used. Most of the missing prefixes are just substituted for numbers, i.e. saying “a thousand kilometers” is much more common that “a megameter”. Of course, this differs depending on context, as a lot of the prefixes become more common within scientific fields where the sizes are common.
On a separate note, even the numbers can be a bit inconsistent. It has bothered me that it’s often common to say “a thousand milliard” instead of “one billion” (also note that we use the long scale).
in school in austria we teach dezimeter (tenth of a meter)
decimeter is a good measure because one cubic decimeter (1 dm³) equals one liter ( 1L )
No, some measurements just aren’t used, even when they’d be a good fit.
Like lengths. We never use anything above km. Even for things like space, we say “million km” rather than gigametre.
The closest we come to hectometre is hectare, which is used for land area.
Where do you live and what is your profession? I have heard anyone use megameter seriously.
