Pretty much what Nada said. I think for hmm the older generation lol our parents and older they'll say. 4:05 as 5 past 4 or 4:50 as 10 till 5. (Again it depends on your parents.) So i think there is some unspoken rule where if the time is less than 10 minutes past the hour or less than 10 minutes till the next hour they'll say the aforementioned. But every other time like 4:20 they'll say oh its four twenty. 4:45 = four forty-five. Oh! 4:30 can also be said as half past four (not half till five-that just sounds reallly weird haha). No one is going to take to time to say 4:37 as "oh it's 37 minutes past 4!" No, it's just four thirty-seven. Hope this helps!