Well we don´t use "A.M." or "P.M.". After twelve we just keep on counting till 24, which would be midnight. e.g. 3:00 PM would be 15:00 Uhr.
Sorry to reveal my ignorance but do you mean you have a metric hour or something ????
In the eastern part of Germany we don´t say " quarter to..." or "quarter past..." (but we understand what is meant whith it) We used to say " quarter ten " which means quarter past nine or " three quarters ten" that means quarter to ten. The people from Westgermany don´t understand this. They believe quarter ten means quarter past ten so they will be one hour to late