Two ways to tell time
The 12-hour system uses a.m. (midnight to noon) and p.m. (noon to midnight). The 24-hour system counts the hours from 0000 to 2359, with no a.m. or p.m.
Key idea / 要点
For p.m. times, add 12 to the hour. For a.m. times, keep the same hour (write two digits).
Changing between them
Worked example / 例题
3:00 p.m. → add 12 to the hour: 3 + 12 = 15 → 1500 hours.
0900 hours → 9 is before noon → 9:00 a.m.
Special times: 12:00 midnight = 0000 hours, and 12:00 noon = 1200 hours.
Remember / 记住
- p.m. hour + 12 = 24-hour time.
- 24-hour times always have 4 digits.
- a.m. hours stay the same number.