wording

SRP & "axis of change"?

I'm reading Bob Martin's principles of OOD, specifically the SRP text, and I understand the spirit of what it's saying pretty well, but I don't quite understand a particular phrasing, from page 2 of the link (page 150 of the book): I paraphrase: It is important to separate these two responsibilities into separate classes because each r...

128 kilobytes or 128 kilobyte? 128 kBs or 128 kB?

I know that it is 128 Euro and 128 apples. I think it is 128 kilobytes, megabytes, gigabytes. Or is it 128 kilobyte, megabyte, gigabyte? If plural is correct, I should really use 128 kBs, MBs, GBs. That looks unfamiliar. Which is correct, plural or singular? Thanks :) ...