The 24 hour clock
Extract from "Numeracy Counts" at Manchester Airport
When reading the time, we normally use the 12 hour clock. This means that there is for example an 8 o'clock in the morning and an 8 o'clock in the evening.
Since the 12 hour clock has the same time shown twice each day, we have to add a.m or p.m after the time
- a.m. (ante meridian) is used for times between midnight and noon
- p.m. (post meridian) is used for times between noon and midnight
Many businesses, including Manchester Airport, operate for 24 hours a day,
7 days a weeks 365 days a year. At the Airport aircraft take off and land
according to a timetable. So that flights take off and land on time and
passengers can catch the correct flight, it is important that everyone is
clear about the timetable and that there is no confusion about the time of
day. For this reason the 24 hour clock is always used.
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The 24 hour clock always uses 4 digits:
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2.15am becomes 02.15
2.15pm becomes 14.15
11.30am becomes 11.30
11.30pm becomes 23.30
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If this is morning time, this clock shows 7.15am. In 24 hour time, this is written as 07.15
If this is evening, this clock shows 7.15pm. In 24 hour time, this is written as 19.15
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If this is morning time, this clock shows 4.30am. In 24 hour time, this is written as 04.30
If this is afternoon, this clock shows 4.30pm. In 24 hour time, this is written as 16.30
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If this is morning time, this clock shows 9.40am. In 24 hour time, this is written as 09.40
If this is evening, this clock shows 9.40pm. In 24 hour time, this is written as 21.40
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If this is morning time, this clock shows 12.05am. In 24 hour time, this is written as 00.05
If this is afternoon, this clock shows 12.05pm. In 24 hour time, this is written as 12.05
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