9) Eighteen (18) Countries use the 12-hour clock: Australia, Bangladesh, Canada, Colombia, Egypt, El Salvador, Honduras, India, Ireland, Jordan, Malaysia, Mexico, New Zealand, Nicaragua, Pakistan, Philippines, Saudi Arabia and U.S. (although the military uses the 24-hour clock).
If you want to set up a meeting that starts at noon, you would set it to start at 12 PM. If you would like to set up a meeting to start at midnight, it would start at 12 AM.
24-Hour Time Format
| am/pm | 24-hour |
|---|
| 12am (midnight) | 00:00 |
| 1am | 01:00 |
| 2am | 02:00 |
| 3am | 03:00 |
If you want to set up a meeting that starts at noon, you would set it to start at 12 PM. If you would like to set up a meeting to start at midnight, it would start at 12 AM.
12:30 a.m. is in the first period which begins at midnight (technically 12:00 a.m.) and the 12:30 p.m. is just after noon (which technically is 12 p.m.).
Another convention sometimes used is that, since 12 noon is by definition neither ante meridiem (before noon) nor post meridiem (after noon), then 12am refers to midnight at the start of the specified day (00:00) and 12pm to midnight at the end of that day (24:00).
Do not use 12 noon or 12 midnight (redundant). Use noon or midnight. Do not use 12 p.m. or 12 a.m. Use noon or midnight.
12am and 12pm are both incorrect. Neither should be used. You should really pay attention to the abbreviation. "a.m." means "ante meridiem" which means "before midday" and p.m. means "post meridiem", which means "after midday".
Anyway, as near as I can tell, the 12-hour clock goes way back to ancient Mesopotamia and Egypt. The Egyptians used a 12-hour sundial to tell time during the daytime and a 12-hour water clock at night. Early mechanical clocks showed all 24 hours, but over time, clockmakers found the 12-hour system simpler and cheaper.
AM/PM (or "12 Hour Clock"): the day is split into: the 12 Hours running from Midnight to Noon (the AM hours), and.
Showing the Time.
| AM | PM |
|---|
| Ante Meridiem* Latin for "before midday" | Post Meridiem* Latin for "after midday" |
| Midnight to Noon | Noon to Midnight |
| 24 Hour: 00:00 to 11:59 | 24 Hour: 12:00 to 23:59 |
Each suceeding day therefore ends at midnight 12:00:00. The next day begins a nanosecond after midnight. So, it seems most accurate to say that each day ends at midnight, and the next day starts “immediately after midnight.â€
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| Current time in 24-hour format | Current time in 12-hour format |
|---|
| 17:00:05 | 05:00:05 PM |
The afternoon is the time of day that starts mid-day and ends in the evening. If you have an afternoon appointment, it's probably some time between 12:00 and 5:00 p.m. It's pretty much agreed that the afternoon begins after noon, or 12:00 p.m., but when the afternoon ends and evening begins is a bit more vague.