How to see it
The 24-hour clock goes round once a day. Afternoon hours add twelve: 3:45 pm is 15:45. Time sums use a jump line, not column subtraction. Go to the next whole hour, then whole hours, then the leftover minutes.
A worked example
09:50 to 10:00 is 10 minutes. 10:00 to 11:00 is one hour. 11:00 to 11:25 is 25 minutes. 10 plus 60 plus 25, 95 minutes, which is one hour 35.
The common mistake: treating minutes as decimals
The trap is subtracting like decimals: 11.25 take 9.50 is 1.75, so one hour 75 minutes. There are only 60 minutes in an hour. If minutes go above 59, something has gone wrong.
Try one
13:40 to 16:15.
- A2 h 35
- B3 h 35
- C2 h 25
- D2 h 75
Show the answerHide the answer
Right: A, 2 h 35
Twenty minutes to 14:00, two hours to 16:00, 15 more.