6:15 .
6:15
A quarter after five, half past 6, a quarter to 7, etc...
Quarter to 10.
It means it's 6:15
It is 06:15:00
6:05 to 6:45 40 minutes
4:45 ; Quarter to 5 5:15 ; Quarter past 5
Quarter past 12 !
A quarter past two!
Both are accepted, but "a quarter after" is preferred in formal writing.
Quarter past is an expression 15 minutes past the current hour. Each quarter of an hour is 15 minutes. So quarter past 10 is equal to 10:15.