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E:\Working\Focus_Learning\Math_Genius_5_(05-10-2023)\Open_Files\CHAP_09
\\November 23, 2023 10:50 AM Surender Prajapati Proof 5 Reader _________________________ Date: ___________________74

1. Two trains depart from Lucknow and arrive at Varanasi as per the time table given
below.
trAIN dePArtUre tIMe FrOM LUCKNOW ArrIVAL tIMe At VArANASI

SUPER FAST 5:10 p.m. 9:20 p.m.
EXPRESS 1730 hours 2400 hours
How much more time does the Express train take as compared to the Super Fast

train?

THE 24-HOUR CLOCK
2400 hours
We normally use the 12-hour clock to measure 0000 hours
or
2300 hours
time. The Railways, the Airlines and some other 2200 hours 11 12 1 0100 hours
0200 hours
organisations work day and night which means for 2100 hours 9 10 midnight 2 3 0300 hours
24 hours. At such places a 24-hour clock is used. 2000 hours 8 4 0400 hours
1900 hours 5 0500 hours
In this system, we use 4 digits to show the time. 7
The first two digits show the hours and the last two 1800 hours 6 p.m. a.m. 6 0600 hours
digits show the minutes. 1700 hours 5 4 7 0700 hours
A day starts at 12 midnight and is written as 0000 1600 hours 3 9 8 0800 hours
0900 hours
hours or 2400 hours. 1500 hours 2 1 noon 11 10 1000 hours
12
1400 hours
12 O’clock midnight is expressed as 0000 hours. 1300 hours 1200 hours 1100 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, 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 Note
with colon and write a.m. next to it. a.m. stands for ante meridiem.
p.m. stands for post meridiem.
For example: 0750 hours = 7:50 a.m.
1057 hours = 10:57 a.m.
rule 2: If 24-hour clock time is greater than 1200 hours, then subtract 1200 hours from
the given time. Separate the hours and minutes with colon. Write p.m. next to it.

For example:
(a) 1300 hours = 1:00 p.m. FACTS

( 1300 hours – 1200 hours = 0100 hours) 2400 hours or 0000 hours
= 12:00 midnight
(b) 2359 hours = 11:59 p.m. ( 2400 hours – 1200 hours
= 1200 hours)
( 2359 hours – 1200 hours = 1159 hours)

teacher’s
tip Explain to the children that if the 24-hour clock time is in between 1200 hours and 2359 hours then it is
written with p.m. and separate the hour and minutes with colon.

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