Time Facts
1 minute = 60 seconds
1 hour = 60 minutes
1 day = 24 hours
1 week = 7 days
1 year = 12 months
1 year = 365/366 days
1 year = 52 weeks
1 decade = 10 years
1 century = 100 years
1 millenium = 1000 years
Clock Facts
1. The
smaller hand is called the hour hand. It moves round the clock twice
in 24 hours.
2. The
bigger hand is called moves 24 times round the clock in 24 hours.
3. The
face of the clock has 12 divisions.
12hour Clock
A day consists of 24 hours. It starts from 12 midnight of one day and
lasts till 12 midnight of the next day. In the 12hour clock, the entire day is
divided into two equal time zones of 12 hours each.
We write a.m. to show morning time,
before noon and after midnight.
a.m. stands for AnteMeridiem, two Latin words meaning
‘Before Noon’.
We write p.m. to show afternoon or
evening time, before midnight and afternoon.
p.m. stands for PostMeridiem,
two Latin words meaning, ‘After Noon’.
1. The time between 12 midnight to
12 noon is written as a.m.
2. The time between 12 noon to 12 midnight is written as p.m.
For example, 8 o’clock in the morning is
written as 8 a.m. and 8 o’clock in the evening is written as 8 p.m.
24hour Clock
In a 24hour clock, the time is counted
from 0 to 24. The time past 12 noon is expressed as 13, 14, 15, ..., 24.
1 p.m. is
expressed as 13:00 hours, 2:30 p.m. as 14:30 hours, 5:30 p.m. is written as
17:30 hours and 8:15 p.m. is written as 20:15 hours.
We can
represent 12hour clock and 24hour clock in the form of a circle. The time in
24hour clock is marked on the outer side and the time in 12hour clock is
marked on the inner side of the circle. We need to add the term ‘hours’ after
the time in 24hour clock.
For
example, 5 o’ clock in the evening is expressed as 5:00 p.m. in 12hour clock
and 17:00 hours in 24hour clock.
Converting 12hour Clock Time into 24hour Clock Time
i.
If the time is in a.m., write the same
time and put hours at the place of a.m.
ii.
If the time is in p.m., add 12 to p.m.
time and put hours at the place of p.m.
Example 1: Convert the following time in 24hour clock time.
a.
7:00 a.m.
b.
9:00 p.m.
c.
10:30 a.m.
d.
11:45 p.m.
Solution:
To convert 12hour clock time, i.e., a.m. and p.m. into 24hour clock, apply
the rules given above.
a. 7:00
a.m. = 07:00 hours
b. 9:00
p.m. = (9:00 + 12) = 21:00 hours
c. 10:30
a.m. = 10:30 hours
d. 11:45
p.m. = (11:45 + 12) = 23:45 hours
Converting 24hour Clock Time into 12hour Clock Time
i.
If the time is less than 12:00 hours,
write the same time and put a.m. at the place of hours.
ii.
If the time is 13:00 hours or more,
subtract 12 from hour time and put p.m. at the place of hours.
iii.
If the time is between 12:00 hours and
13:00 hours, put p.m. at the place of hours.
Example 2: Convert the following time in 12hour clock time.
a. 04:00
hours
b. 18:00
hours
c. 12:25
hours
d. 22:15
hours
Solution:
To convert 24hour clock time, into 12hour clock, rules are as follows:
a. 04:00
hours = 4:00 a.m.
b. 18:00
hours = 18:00 – 12:00 = 6:00 p.m.
c. 12:25
hours = 12:25 p.m.
d. 22:15
hours = 22:15 – 12:00 = 10:15 p.m.
Calculating Time Duration
To find the time duration of any event,
i.
If the starting time and finishing time
both are in a.m. or p.m., then directly subtract the starting time from the
finishing time.
ii.
If one of the starting time and finishing
time are in a.m. and the other is in p.m., convert both the times in 24hour
clock time and then subtract the starting time from finishing time.
Example 3: Nidhi started for her office at 8:35 a.m. and
reached at 9:45 a.m. How much time did she take to reach her office?
Solution: Since both the times are in a.m., we directly
subtract the starting time from the reaching time.
Reaching time = 9:45 a.m.
Starting time = 8:35 a.m.
Time duration = 9:45 – 8:35 = 1:10
Thus, she took 1 hour 10 minutes to reach her office.
Example 4: An ODI match started at 9:30 a.m. and got over at 5:00 p.m. What was
the total duration of the match?
Solution: Since the starting
time is in a.m. and the finishing time is in p.m., we convert both the times in
24hour clock time and then subtract.
Finishing
time = 5:00 p.m. = 5:00 + 12:00 = 17:00 hours
Starting
time = 9:30 a.m. = 9:30 hours
Time
duration = 17:00 – 9:30 = 7:30 hours
Thus, the
total duration of the match was 7 hours 30 minutes.
Calculating Number of Days
To
calculate the number of days between two events, follow these steps:
Step 1: Make a table showing valid days in each month for the given period.
Step 2: Remove the starting day from the computation.
Step 3: Put all months before the ending month with number of days.
Step 4: Put all days of the ending month.
Step 5: Add and give the
total.
Example 5: Rohit went to USA for some business work on 25^{th}
May 2019 and came back to his place on 11^{th} September 2019. For how
many days he was out from his place?
Solution: Find the number of days in each month. 25^{th}
May is not to be included and 11^{th} September is to be included.
Month

Number of days

May

6

June

30

July

31

August

31

September

11

Total

109

Thus, Rohit was out for 109 days from his own place.