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E:\Working\Brother_Education\Preparatory_Stage_Maths-4\Open_Files\Chap-12
\\November 1, 2023 12:06 PM Bharat Arora P-5 Reader _________________________ Date: ___________________

Practice Time 12B

1. Observe the following given clocks and answer, how many seconds have passed
as the second hand moves from one number to the other?

11 12 1 11 12 1 11 12 1 11 12 1
10 2 10 2 10 2 10 2
9 3 seconds 9 3 seconds 9 3 seconds 9 3
later
later
later
8 4 8 4 8 4 8 4
7 6 5 7 6 5 7 6 5 7 6 5

2. Draw the missing second hand on the given clocks.

11 12 1 11 12 1 11 12 1 11 12 1
10 2 10 2 10 2 10 2
9 3 15 seconds 9 3 25 seconds 9 3 45 seconds 9 3
later
later
later
8 4 8 4 8 4 8 4
7 6 5 7 6 5 7 6 5 7 6 5

THE 24-HOUR CLOCK

We normally use the 12-hour clock to measure 2400 hours
or
time. The railways, the airlines and some other 2300 hours 0000 hours 0100 hours
2200 hours 11 12 1 0200 hours
organisations work day and night which means 2100 hours 9 10 midnight 2 3 0300 hours
for 24 hours. At such places a 24-hour clock is 2000 hours 8 4 0400 hours
1900 hours 7 5 0500 hours
used.
1800 hours 6 p.m. a.m. 6 0600 hours
In this system, we use 4 digits to show the time. 1700 hours 5 7 0700 hours

The first two digits show the hours and the last 1600 hours 4 3 9 8 0800 hours

0900 hours
two digits show the minutes. 1500 hours 2 1 noon 11 10 1000 hours
12
1400 hours
1300 hours 1100 hours
A day starts at 12 midnight and is written as 1200 hours
0000 hours or 2400 hours.
12 O’clock midnight is expressed as 0000 hours.
12 O’clock at noon is expressed as 1200 hours.

Conversion of 24-hour Clock Time to 12-hour Clock Time

To convert 24-hour clock time to 12-hour clock time, we follow the following rules.

Rule 1: If 24-hour clock time is less than 1200 hours, write hours and minutes side
by side by separating them with a colon and write a.m. next to it.

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