Just to go back towards the beginning of this thread for a moment, the question was asked:

OK. And what does the K come from to mean thousand? kilo?

FWIW there is a convention in the SI unit system that units that are named after a person take a capital letter whereas units that are not take a lower case letter.

So, for example, the unit of vibration is named after a man called Hertz and so one thousand Hertz would be shown as 1000Hz whereas one thousand kilometers would be shown as 1000km.