Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
12-hour clocks use 'AM' (ante meridiem) for morning and 'PM' (post meridiem) for afternoon/evening.
24-hour clocks use four digits and do not use AM or PM (e.g., 08:00 or 20:00).
Midday is 12:00 PM in the 12-hour system and 12:00 in the 24-hour system.
Midnight is 12:00 AM in the 12-hour system and 00:00 in the 24-hour system.
To convert PM times (from 1:00 PM to 11:59 PM) to 24-hour time, add 12 to the hours.
To convert 24-hour times (from 13:00 to 23:59) to 12-hour time, subtract 12 from the hours and add PM.
📐Formulae
💡Examples
Problem 1:
Convert 4:25 PM into 24-hour clock format.
Solution:
16:25
Explanation:
Since the time is in the PM, we add 12 to the hour. . The minutes stay the same, so it becomes 16:25.
Problem 2:
Convert 08:10 into 12-hour clock format.
Solution:
8:10 AM
Explanation:
Because the hour is less than 12 and it is not 00, it is in the morning (AM). We remove the leading zero and add the 'AM' label.
Problem 3:
A train departs at 21:45. What time is this on a 12-hour clock?
Solution:
9:45 PM
Explanation:
Since the hour 21 is greater than 12, we subtract 12 from the hours () and add the 'PM' suffix.
Problem 4:
Convert 12:05 AM to 24-hour clock format.
Solution:
00:05
Explanation:
In the 24-hour clock, the first hour of the day (12:00 AM to 12:59 AM) is represented by 00. Therefore, 12:05 AM becomes 00:05.