aside: the little-k thing. SI has a beautifully simple rule, capital letters for prefixes >1, small letters for prefixes <1. So this disambiguates between a millivolts (mV) and megavolts (MV).

But, and there’s always a but. The kilogram was the first SI unit, before they’d really thought it through. So we got both a lower-case k breaking such a beautifully simple rule, and the kilogram as a base unit instead of a gram. The Kilogram is metric’s “screw it, we’ll do it live”.