> while I could theoretically use decameters, in practice average people seem to only use Everyone uses decimeters where I'm from, it isn't strange at all and

> while I could theoretically use decameters, in practice average people seem to only use Everyone uses decimeters where I'm from, it isn't strange at all and everyone understands it. People use mm, cm, dm, m or km depending on what fits best, that gives you a much more fine grained set of lengths to talk about and it is trivial to convert between them so people don't have to think about it. Maybe countries that doesn't use metric in everyday life just teaches you cm and m, but there is no reason to just stay with those. The confusion is maybe that we don't mix units, you don't say "1 meter 8 decimeters and 3 centimeters", you just use one, and in those since the accuracy is in centimetetrs you just use centimeters, or meters straight. But if you talk about a distance of around 30 centimeters people just say 3 decimeters, and since everyone has worked a lot with those before they take their mental decimeter times 3 and they know the length.