Reading 24-hour clock time
Topic Notes
In this lesson, we will learn:
- 24-hour clock time is used instead of 12-hour clock time to avoid being confused about AM or PM
- There are 24 hours in a day, so instead of the hours being labelled 1-12 AM or 1-12 PM, we can label them from 1-24 instead.
- There are rules for converting between 12-hour clock time and 24-hour clock time (and vice versa)
Notes:
- Using 12-hour clock time can be confusing because you might not know if someone is telling you a time for AM or PM (ex. is it 6 o’clock in the morning or evening?)
- By using 24-hour clock time, we can avoid the confusion of not knowing AM/PM
- There are 24 hours in a day
- The previous days ends, and the new day starts at midnight (12:00 AM)
- The middle of the day is right at noon (12:00 PM)
- For 24-hour time, you say the hours directly from 00 until 24 (or back to 00)
![Time: Reading 24-Hour Clock Time](
https://dmn92m25mtw4z.cloudfront.net/img_set/math5-13-3-x-1/v1/math5-13-3-x-1-707w.png)
- This table shows all the equivalent times for the 12-hour clock and 24-hour clock:
![Time: Reading 24-Hour Clock Time](
https://dmn92m25mtw4z.cloudfront.net/img_set/math5-13-3-x-2/v1/math5-13-3-x-2-1027w.png)
- When it goes to midnight (12AM), it becomes 24:00 which is the same as 00:00
- Do not use this table when doing the practice questions; only for checking
- To convert from AM/PM time (12-hour clock time) to 24-hour time:
- if AM, keep the same (add leading 0)
- if PM add 12
- Ex. (8:46AM = 08:46), (5:13PM = 17:13), (12:07AM = 00:07)
- To convert from 24-hour time to AM/PM time :
- if < 12, keep same, remove leading 0, and write AM
- if > 12 subtract 12 and write PM
- Ex. (09:54 = 9:54AM), (22:38 = 10:38PM), (00:16 = 12:16AM)
1. Minutes: stay the same
2. Hours:
3. Exceptions: 12AM = 00h, 12PM = 12h
4. Minutes: stay the same
5. Hours
6. Exceptions: 00:00 = 12AM and 12:00 = 12PM