The idea, step by step
Bridge through a convenient time
Elapsed time is the amount of time between a start and a finish. It is a duration, so write minutes or hours as well as the number. A clock hour has 60 minutes, not 100.
One useful method is to jump forward to the next full hour, then continue to the finish. Add the jumps. You may also convert each time into minutes after midnight when both are on the same day.
Keep track of the day
When a journey crosses midnight, the next day begins at 00:00. Count to midnight first, then from midnight to the arrival. Do not subtract the smaller-looking clock number from the larger one without checking the day.
Check your result by adding the duration back to the departure. For a finishing-time problem, split a long duration into hours and minutes before adding it.
A common trap
Saying 09:25 to 10:05 is 80 minutes by treating the times as ordinary decimal numbers.
Instead: There are 35 minutes to 10:00, then 5 minutes more: 40 minutes.
See the thinking
Cross an hour
A train departs at 08:47 and arrives at 10:12 on the same day. How long is the trip?
- 08:47 to 09:00 is 13 minutes.
- 09:00 to 10:00 is 60 minutes, then 12 minutes to 10:12.
- 13 + 60 + 12 = 85 minutes.
Cross midnight
A bus leaves at 23:35 and arrives at 00:20 the next day. Find the journey time.
- 23:35 to midnight is 25 minutes.
- Midnight to 00:20 is 20 minutes.
- 25 + 20 = 45 minutes.
Check your understanding
How long is 14:50 to 15:15?
Show answer
25 minutes
10 minutes reach 15:00, then 15 more minutes reach 15:15.
Your turn
6 questions · 13 marks · Work at your own pace.
Read the questions online
- Find the elapsed time from 09:25 to 10:05.2 marks
- Find the elapsed time from 13:48 to 15:06.2 marks
- A journey starts at 11:40 and lasts 55 minutes. When does it finish?2 marks
- You must arrive at 16:05 after a trip of 1 hour 25 minutes. What is the latest departure time?2 marks
- A coach leaves at 22:50 and arrives at 01:15 the next day. Find its journey time.2 marks
- An outing starts at 08:40. It has 30 minutes of travel, a 15-minute wait, a 45-minute activity and 20 minutes of travel home. When does it finish?3 marks
Read the worked solutions
Equivalent correct methods earn the corresponding marks. Include units where asked.
- Find the elapsed time from 09:25 to 10:05.2 marks
09:25 to 10:00 is 35 minutes.
Add 5 minutes: 40 minutes.
40 minutes - Find the elapsed time from 13:48 to 15:06.2 marks
12 minutes to 14:00, then 60 minutes to 15:00, then 6 minutes.
12 + 60 + 6 = 78.
78 minutes, or 1 hour 18 minutes - A journey starts at 11:40 and lasts 55 minutes. When does it finish?2 marks
20 minutes reach 12:00.
There are 35 minutes left, so the finish is 12:35.
12:35 - You must arrive at 16:05 after a trip of 1 hour 25 minutes. What is the latest departure time?2 marks
Subtract 1 hour to 15:05.
Subtract 25 minutes to 14:40.
14:40 - A coach leaves at 22:50 and arrives at 01:15 the next day. Find its journey time.2 marks
70 minutes reach midnight.
75 more minutes reach 01:15.
70 + 75 = 145 minutes.
2 hours 25 minutes, or 145 minutes - An outing starts at 08:40. It has 30 minutes of travel, a 15-minute wait, a 45-minute activity and 20 minutes of travel home. When does it finish?3 marks
30 + 15 + 45 + 20 = 110 minutes.
08:40 + 1 hour 50 minutes = 10:30.
10:30
Curriculum reference & lesson scope
Australian Curriculum v9 / SA Curriculum Mathematics
Year 6: itineraries, elapsed time and feasible journey planning, including connections and 24-hour time.
Official curriculum source ↗