12-hour and 24-hour clock
Time is measured using either the \(12\)-hour clock or the \(24\)-hour clock.
12-hour clock
The \(12\)-hour clock notation uses am and pm to indicate morning and afternoon.
- \({am}\) is the time from \(12\) midnight and before \(12\) noon (\(12.00pm\) is midday)
- \({pm}\) is the time from \(12\) midday and before \(12\) midnight (\(12.00am\) is midnight)
For example
- \[6.23am\]
- \[7.45pm\]
24-hour clock
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.
For example
- \(6.23pm\) becomes \((6.23 + 12) = \text{18:23}\)
- \(7.45pm\) becomes \((7.45 + 12) = \text{19:45}\)
The \(24\)-hour clock always uses \(4\) digits, so for any time before \(\text{10:00}\) a zero is placed at the beginning.
For example
- \(\text{01:00}\) means \(1.00am\)
- \(\text{13:00}\) means \(1.00pm\)
- \(\text{04:00}\) means \(4.00am\)
- \(\text{16:00}\) means \(4.00pm\)
- Question
Copy and complete the following table, then check your answers.