Are you sure? Intuitively I would have said, that "I'm one eighty tall" is an abbreviation for "I'm one [meter] [and] 80 [centimeter] tall".
Thinking about it, if I measure something with a folding ruler, I would more naturally say "it's one meter eighty long" (German native speaker here, as already said elsewhere, with other languages YMMV).
But the point still stands. In metric, you can slap the numbers together or separate them, convert them to different units or sprinkle easily units in between or not. It all works. At worst it is just moving the decimal point around or adding/removing zeros. Very easily done in your head.
Thinking about it, if I measure something with a folding ruler, I would more naturally say "it's one meter eighty long" (German native speaker here, as already said elsewhere, with other languages YMMV).
But the point still stands. In metric, you can slap the numbers together or separate them, convert them to different units or sprinkle easily units in between or not. It all works. At worst it is just moving the decimal point around or adding/removing zeros. Very easily done in your head.