When I was at school (forty-five years ago or so) we were taught that it was a mistake to write numbers of any kind as digits. I suppose our teacher would have made an exception for telephone numbers, and possibly dates like "1066", but the overall principle was pretty rigid. "7 o'clock"? Never in 1,000,000 years.Is it possible to write seven o'clock (or any other time) or is it a mistake?
Have you, SDG?Have you reviewed the existing threads concerning "o'clock?"