[vidarh]

> is that the metric system seems to have an extra 1,000 that may or may not apply.

You may be getting confused over prefixes vs base units because some pairs of prefixes and base units are so common they sort-of end up treated as a unit in themselves.

E.g. "kilo" is not a metric unit, but sometimes used as short for "kilogram", where "kilo" is the prefix for 1000 and "gram" is the metric unit. These prefixes are consistent for all metric units.

[avmich]

"Kilometer" is another popular unit, which is never called "kilo", lately I heard it's informally called "click" in US. Logic is the same, kilometer means a thousand meters, and meter is the base unit of length.

[papercrane]

I once worked with someone from Egypt who used "kilo" for kilometers. He's the only person I've met who did that. I've no idea if that was just a personal quirk or if that was a common shortening elsewhere in the world.

[littlestymaar]

> where "kilo" is the prefix for 1000 and "gram" is the metric unit.

Fun fact: the metric unit for mass is … the kilogram, not the gram because f*ck consistency.

[avmich]

No, just because historical :) . There's the system centimeter-gram-second, which is used e.g. for electromagnetic physics, it has its own quirks, at least with "centi"-meter unit name.