It's correct and common usage..."quarter of" is the same as a "quarter
before". One of many definitions of "of" includes: Away from or
distance from.

The full sentence would be: It is one quarter of an hour before (away
from) nine hours on the clock. In the interest of brevity it becomes:
It's a quarter of nine.

Tony Calguire wrote in message ...
BDK wrote:


How old are you? I can't believe anyone over 25 hasn't
heard the term before. As others have posted, a
"quarter" is 15 minutes, AKA 1/4 of an hour...



The original poster's problem was not with the word "quarter", but with
the word "of". The phrase "a quarter of nine" is completely
meaningless... what exactly is one-fourth of nine o'clock, anyway?
9:15? But "a quarter of nine" actually means 8:45.