Mathematics (Core)Exam code: 0580
Time, Currency and Conversions
Number
Reading each format
- A 12-hour clock runs twice through the day, distinguished by am and pm
- am covers midnight through to midday, and pm covers midday through to midnight
- A 24-hour clock runs once through the day using four digits, from 00 00 at midnight to 23 59
- Converting from pm to 24-hour form means adding 12 to the hours
- 7.40 pm becomes 19 40
- The hours before 10 am keep a leading zero
- 6.05 am becomes 06 05
The two awkward cases
- Midnight is 00 00 in 24-hour form and 12 am in 12-hour form
- Midday is 12 00 and 12 pm, so 12 pm is not 24 00
Exam tip
No am or pm on a 24-hour time
A 24-hour time is a time of day: it takes no am or pm, and it is not a length of time. The schemes take the final mark away from answers such as 19 40 pm, 07:15am or 19 hr 40 min. Write 19 40 or 19:40, or 7.40 pm when the question does not ask for the 24-hour clock.