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E:\Working\Orange_Education\Math_Genius_4\Open_Files\Chap-11
\\September 30, 2025 12:00 PM Bharat Arora P-9 Reader _________________________ Date: ___________________74

Practice time 11B

1. Look at the following clocks. How many seconds have passed as the second
hand moves from one number to the next?

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

24-Hour CloCk

We know that a day has 24 hours. The hour 2400 hours
or
2300 hours
hand takes 2 rounds of the clock to cover 24 2200 hours 11 0000 hours 1 0100 hours
0200 hours
12
hours. We use a.m. (ante meridiem) for the 2100 hours 9 10 midnight 2 3 0300 hours
time from 12 midnight to 12 noon and p.m. 2000 hours 8 4 0400 hours
(post meridiem) for the time from 12 noon 1900 hours 7 5 0500 hours
to 12 midnight. 1800 hours 6 p.m. a.m. 6 0600 hours

We commonly use the 12-hour clock to see the 1700 hours 5 4 8 7 0700 hours
time. But railways, airlines and armed forces 1600 hours 3 2 noon 10 9 0800 hours
1500 hours
0900 hours
use the 24-hour clock to read and tell time. 1400 hours 1 12 11 1000 hours
1300 hours 1100 hours
Look at the clocks shown below. 1200 hours

11 12 1 2 Be Aware
20:00 9 3 Analog The 24-hour clock does not use
10
clock
a.m. or p.m. to show the time.
digital clock 8 7 6 5 4

Both clocks show the same time, that is, 8 o’clock at night. The digital clock shows
the time in the 24-hour format in the form hh:mm. The first two digits in the 24-
hour clock show the hours and the last two digits show the minutes.

In a 24-hour clock, 12 midnight is denoted as 00:00 hours or as 24:00 hours.

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