A.M and P.M / 12 Hour Clock

Most of the clocks that we see are 12-hour clock. In 12 hour clock, a full day (i.e. 24 hours) are divided into two parts of 12 hour each. The first part is known as a.m. or A.M. (ante meridian), which means before noon {i.e. time between midnight (0:00) & noon (12:00)} and second part is known as p.m. or P.M. (post meridian), which means after noon {i.e. time between noon (12:00) & midnight (0:00)}.

Technically, midnight and noon, each hour of the day is suffixed by am or pm to identify whether the hour is being referred is the morning, afternoon or evening.  But most digital clocks show 12 am and 12 pm to specify midnight and noon, respectively.

We generally use 12 hours clock time in which hour hand takes two round of the face of the clock in 24 hours.

The 24 Hours Clock Time

Digital watches show time in 24 hours clock time. In case of 24-hour clock, the day runs from midnight to midnight and is divided into 24 hours, which shows the hours passed since midnight, from 0 to 23. In 24 hours clock time is shown in 4 digits.

12 o’clock midnight is expressed as 0000 hrs. and 12 o’clock noon is expressed as 1200 hrs.

Converting 24 hours clock time to 12 hours clock time.

In this case use a.m. if number of hours is less than 12 and if numbers of hours is more than 12 then subtract 12 from the number of hours given and use p.m.

Example 1:  0400 hrs.

Here, number of hours is less than 12. So, time according to 12 hours clock time is 4:00 a.m.

Example 2:  1640 hrs.

Here, number of hours is more than 12. So, we will subtract 12 from 16 hours and add p.m.

Time according to 12 hours clock time is (16 – 12 = 4) hrs. = 4:40 p.m.

Converting 12 hours clock time to 24 hours clock time.

If the time given is before 1 p.m., simply write the hours and minutes in the 24 hours clock time format. Beyond 1 p.m. add 12 to the hour part of the given time.

Example 1: 5:25 a.m.

Here time is before 1 p.m. So, we will simply write the time in 24 hours clock time format i.e. 0525 hrs.

Example 2: 6:10 p.m.

Here time is beyond 1 p.m. So, we will add 12 to the hour part of the given time.

(6 + 12 = 18) hrs.

1810 hrs.