Page 135 - Maths Class 05

The 24-hour Clock
0500 0600 0700
In the 24-hour clock, there are no ‘am’ and ‘pm’ 0400 5 6 7 0800
0300 4 8 0900
labels. 3 9
0200
2 10 1000
The hours start at zero and go throughout to 23. All 0100 1 11 1100
24 hours clock times should be written hh:mm or 0000 hours 12 midnight a.m. 12 noon 1200 hours
p.m.
2400
hh:mm:ss. Where h is the hour, m is the minute and s 2300 11 1 1300
10 2
2200 1400
is the second. Sometimes, the colons are omitted 9 3
2100 8 4 1500
between the hours and minutes. 2000 7 6 5 1600
1900 1700
The Railways, the Airlines and some other 1800
organisations work day and night which mean for 24-hours. At such places a 24-hour clock

is used. Look at the 24-hour clock shown here.
Converting from One Unit to Another

Let us learn to convert from bigger unit to a smaller unit.
1 hour = 60 minutes

1 minute = 60 seconds

Converting minutes into seconds

Example : Convert 8 minutes into seconds.

Solution : 1 minute = 60 seconds

8 minutes = 8 × 60 seconds

= 480 seconds

1
4
Example : Convert minutes into seconds.
2

Solution : 1 minute = 60 seconds
4 minutes = 4 × 60 seconds

= 240 seconds

1
minute = 30 seconds
2
1
4 minutes = 240 + 30 seconds = 270 seconds
2

Know
Know
Know
Get
Get
Get to
to
To convert hours into minutes or minutes into seconds we multiply by 60.

Mathematics-5 135