The 24-hour clock does not require the use of am or pm. Afternoon is indicated by a number bigger than 12.
When converting from the 12-hour clock to the 24-hour clock remember: for any time after 12.59pm, add 12 to the hours.
- 6.23pm becomes (6.23+12)=18:23
- 7.45pm becomes (7.45+12)=19:45
The 24-hour clock always uses 4 digits, so for any time before 10:00 a zero is placed at the beginning.
- 01:00 means 1.00am
- 13:00 means 1.00pm
- 04:00 means 4.00am