Time
Time units & conversions
Time does not work in tens. Sixty seconds, sixty minutes, twenty-four hours — the numbers have to be learnt.
The units
60 seconds = 1 minute 60 minutes = 1 hour 24 hours = 1 day 7 days = 1 week Unlike most measures, time is not based on tens. That is why you cannot simply move the decimal point.
Converting to smaller units
To go from bigger units to smaller ones, MULTIPLY. 2 hours = 2 × 60 = 120 minutes 1.5 minutes = 1.5 × 60 = 90 seconds 3 days = 3 × 24 = 72 hours The number gets bigger, which makes sense — a smaller unit means you need more of them.
Converting to bigger units
To go from smaller units to bigger ones, DIVIDE. 120 minutes = 120 ÷ 60 = 2 hours 90 seconds = 90 ÷ 60 = 1.5 minutes Check your answer is sensible: converting to a bigger unit must give a smaller number.
Halves and quarters
Half and quarter units come up constantly: 0.5 of a day = 12 hours 1.5 days = 36 hours 0.5 of an hour = 30 minutes 2.5 hours = 150 minutes 0.5 of a minute = 30 seconds Work out one whole unit first, then take the half of it — that is usually quicker than multiplying a decimal.
Worked examples
2.5 hours in minutes
- 1 hour is 60 minutes, so 2 hours is 120.
- Half an hour is 30 minutes.
- 120 + 30 = 150.
Answer: 2.5 hours = 150 minutes
1.5 minutes in seconds
- 1 minute is 60 seconds.
- Half a minute is 30 seconds.
Answer: 1.5 minutes = 90 seconds
1.5 days in hours
- 1 day is 24 hours.
- Half a day is 12 hours.
- 24 + 12 = 36.
Answer: 1.5 days = 36 hours
120 minutes in hours
- Going to a bigger unit, so divide.
- 120 ÷ 60 = 2.
Answer: 120 minutes = 2 hours
3 days in hours
- 1 day is 24 hours.
- 3 × 24 = 72.
Answer: 3 days = 72 hours
Where you see this in real life
- A recipe saying 'bake for 1.5 hours' — you set a timer for 90 minutes.
- A film lasting 150 minutes is 2.5 hours long.
- Working out how many hours are in a long weekend.
Key words
- Second
- The smallest common unit of time.
- Minute
- 60 seconds.
- Hour
- 60 minutes.
- Day
- 24 hours.
- Convert
- Change into a different unit.
- Duration
- How long something lasts.