Reading through some comments on Bad Astronomy BLOG I came across this.
"11 kilopicoseconds as Earth’s escape velocity makes no sense.
At first I didn't understand what the commenter was talking about. "kilopicoseconds, wtf" I thought to myself. After reading the colostate URL info it struck me, Phil had written "11 kps" in his blog.
"The symbol for a compound unit that is a quotient of two units is indicated by a solidus or by a negative exponent.
* RIGHT: km/h or km·h-1 (for kilometers per hour)
* WRONG: kmph or kph (do not use p as a symbol for "per".)
* BUT: It is correct to say or write "kilometers per hour"."
I know lots of people that use p as "per" but now I know better. I'll stick with the "/" in the future.