How does the thing for metric system, "King Hector Drinks Units of Delicious Milk" work? What does it stand for?

2 answers

Kilometre,Hectometre,Decametre,Decimetre and Meter I think that's how it goes this saying that you have also has other ones the same but a little different words.
King Hector's Daffy Mother Drinks Chocolate Milk

The order of prefixes in the metric system, for every power of ten from 3 to -3, is Kilometer, Hectometer, Decameter, Meter, Decimeter, Centimeter, Millimeter:

I hardly ever hear anyone use hectometer or decameter though and more important would be micrometer and nanometer in this day and age.