Time

t

 

60 seconds = 1 minute
60 minutes = 1 hour
24 hours = 1 day
7 days = 1 week
52 weeks = 1 year

 365 days = normal year
366 days = leap year

   

  Leap years are divisible by 4
Centuries are not leap years unless divisible by 400

 

Calendar

January   31 days
February   28 days (29 in leap year)
March     31 days
April        30 days
May     31 days
June           30 days
July         31 days
August     31 days
September  30 days
October   31 days
November  30 days
December  31 days 

12 hour and 24 hour clock

12 hour clock times are written with
am to represent morning
and pm to represent afternoon.
A colon is used to separate minutes.

Examples
9 :30 am  is half past nine in the morning.
9: 37 pm  is 23 minutes to ten in the evening.

 

24 hour clock times are written with 2 digits to show hours
and a colon to separate minutes.

 

Examples
09 :30  is half past nine in the morning.
21: 37  is 23 minutes to ten in the evening.

 

Military usage of 24 hour clock times
drops the  colon
and adds the word hrs.

Examples
09 30 hrs  is half past nine in the morning.
21 37 hrs  is 23 minutes to ten in the evening.

Converting between 12 hour and 24 hour clock times

     To convert from 12 hour clock times to 24 hour clock times,

Examples
9:30  am    =  09:30   or   09 30 hrs
3.15 pm   = 15:15    or  15 15 hrs

 

 To convert from 24 hour clock times to 12 hour clock times,

 

Examples
03:15  = 3:15  am   
23:23   = 11:23 pm
11 27 hrs = 11:27 am
21 00 hrs = 9 pm

 

Conversion table

 

Time

12 hour

 

24 hour

Military

Midnight

=

00:00

00 00 hrs

1 am
2 am
3 am
4 am
5 am
6 am
7 am
8 am
9 am
10 am
11 am
Midday
1 pm
2 pm
3 pm
4 pm
5 pm
6 pm
7 pm
8 pm
9 pm
10 pm
11 pm

 

01:00
02:00
03:00
04:00
05:00
06:00
07:00
08:00
09:00
10:00
11:00
12:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
20:00
21:00
22:00
23:00

01 00 hrs
02 00hrs
03 00 hrs
04 00 hrs
05 00 hrs
06 00 hrs
07 00 hrs
08 00 hrs
09 00 hrs
10 00 hrs
11 00 hrs
12 00 hrs
13 00 hrs
14 00 hrs
15 00 hrs
16 00 hrs
17 00 hrs
18 00 hrs
19 00 hrs
20 00 hrs
21 00 hrs
22 00 hrs
23 00 hrs

Midnight

 

00:00

00 00 hrs

Calculations with time

Do not use your calculator – unless you are using the Deg,Hour,Min function.
Otherwise, your answer will not be converted properly.

Examples

   calculate the time difference between
a) 11:07 and 11:30        b) 11:07 and 12:00

 

3

 

examples 
calculate the time difference between :-

a) 11:07  and 11:30       

2

b) 11:07 and 12:00    

3

 

C) 09:45 and 17:38

4

 

Remember

4.1 hrs = 4 hours 6 minutes , not 4 hours 10 minutes.

Hours

Minutes

1

60

0.05

3

0.1

6

0.15

9

0.2

12

0.25

15

0.3

18

0.35

21

0.4

24

0.45

27

0.5

30

0.55

33

0.6

36

0.65

39

0.7

42

0.75

45

0.8

48

0.85

51

0.9

54

0.95

57

 

World Time

 

World Time calculator

Time zone codes

Why change Time ?

 

 

© Alexander Forrest