In reference to ‘thousands’, I was wondering recently whether the correct usage was “k” or “K”. It seems that it is entirely subjective, but lower case “k” is the common usage when denoting thousands of dollars.
During my research into the question I came across an interesting discussion on mathforum.org about this, and encountered usage of “M” to denote thousands, “MM” to denote millions. I’ve not noticed this before (perhaps it is a US peculiarity). Good to know.