Page 142 - Start Up Mathematics_4

24-Hour Clock

Now I know how to write time in a.m. and p.m. Is there any
other way of writing time?

Yes there is one 24-hour clock. Its very simple to understand.

24-hour clocks are mostly used by the railways, airlines and defence
forces.

In a 24-hour clock, the day runs from midnight to midnight and is
divided into 24 hours.
• The format of a 24-hour clock is hours : minutes or
hours : minutes : seconds. It can also be written as hours
followed by minutes like 1140 hours. In this, the first two digits
stand for hours and the next two digits stand for minutes.

• 12 o’clock midnight is written as 0000 hours or 00:00 to begin a day. It is also written
as 2400 hours or 24:00 to mean the end of a day. Thus, 24:00 of a day is the same as
00:00 of the next day.
• 12 o’clock noon is written as 1200 hours or 12:00.
• Numbers below 10 are written with a zero before them. For example, seven thirty is
written as 0730 hours or 07:30.

• In a 24-hour clock, after 1200 hours, the time is read Know More
as: 1200 hours + 0100 hours = 1300 hours The system of 24-hour clock is
1200 hours + 0200 hours = 1400 hours known as military time in
US and Canada. In some
1200 hours + 0330 hours = 1530 hours, and so on. parts of the world it is

known as railway time.
Conversion of Time

We can convert 24-hour clock time to 12-hour clock time by using the following conversion
table.

24-hour clock 12-hour clock

00:00/0000 hours 12:00 midnight
01:00/0100 hours 1:00 a.m.
02:00/0200 hours 2:00 a.m.

03:00/0300 hours 3:00 a.m.
04:00/0400 hours 4:00 a.m.
05:00/0500 hours 5:00 a.m.
06:00/0600 hours 6:00 a.m.

contd…

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