Thursday, December 10, 2009
12-hour or 24-hour clock?
Do we use the 12-hour or the 24-hour clock more?
The answer is the second.
This system is the most commonly used time notation in the world today. Popularly known as military time, astronomical time, railway time or continental time. It is also the international standard notation of time.
It is used in many areas like:
• Medicine - to record all documentation of events occurring during a patient’s hospitalization;
• Timetables/schedules – to tell arrival and departure times in railway stations and airports
• Astronomy/Space exploration – to record observation times and space launches
• Armed forces – to refer to time in general in the army, navy and air force
• Computer support - In most countries, computers by default show the time in 24-hour notation.
For example, Windows XP activates the 12-hour notation only if a computer's language and region settings are
- English (only in Australia, Belize, Canada, Caribbean, Jamaica, New Zealand, Philippines, Trinidad, South Africa, United States, and Zimbabwe)
- Spanish (only in Mexico and parts of South America)
So how do we say it?
The 24 hour clock is similar to how we say the year in English:
1997 – nineteen ninety-seven
18:30 – eighteen thirty
With on the hour (____:00) times, we usually say:
18:00 – eighteen o’clock or eighteen hundred hours
24:00 – twenty-four o’clock or twenty-four hundred hours
Some more examples:
14:45 – fourteen forty-five
23:05 – twenty-three oh five
So the next time you ask for the time or someone asks for it, remember you can use either the 12-hour system or the 24-hour system.