Maths · Number. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
Time does not work in tens. There are 60 seconds in a minute and 60 minutes in an hour, so you cannot add or subtract times as if they were decimals. Work in hours and minutes separately, or count on in stages.
The 24-hour clock runs from 00:00 (midnight) to 23:59. From 1:00 pm onwards, the 24-hour time is 12 more than the pm time, so 3:40 pm is 15:40. A journey that passes midnight starts again from 00:00.
To find how long something lasts, count on from the start to the next whole hour, then to the last whole hour, then to the end time. In a timetable, read along the row of the place you want.
Students treat 1 hour as 100 minutes, for example writing 1 hour 30 minutes as 1.30 hours or subtracting times like ordinary decimals. Remember that 1 hour 30 minutes is 1.5 hours, and count on in stages when you subtract.
Answer: 213 minutes
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