Time sizes: convert
You learn to convert units of time, even with a decimal point, like 2.5 hours to minutes.
How to work it out
- Find the step between the two units: a day is 24 hours, an hour is 60 minutes.
- If you go to a smaller unit, multiply by that step.
- If you go to a larger unit, divide by that step.
- If the time has a decimal point, work out the whole part and the part after the decimal point separately.
day× 24hour× 60minute× 60second
A worked example
3 days = ? hours
- From days to hours: 1 day is 24 hours.
- Multiply by 24: 3 × 24 = 72.
- It is 72 hours.
More examples
2.5 hours = ? minutes
- From hours to minutes: 1 hour is 60 minutes.
- Do the whole part: 2 × 60 = 120.
- Do the decimal part: 0.5 × 60 = 30.
- Add them: 120 + 30 = 150.
- It is 150 minutes.
90 minutes = ? hours
- From minutes to hours: divide by 60.
- 90 ÷ 60 = 1.5.
- It is 1.5 hours.
Try it yourself
1 day = ? hours
1 year = ? months
Watch out
You multiply by 10, as with other units: 3 days becomes 30 hours.
With time the steps are different. A day is 24 hours, not 10 hours.
You forget the step: 2.5 hours becomes 2.5 minutes.
An hour is 60 minutes. So 2.5 times 60.
Tips
- A day is 24 hours, an hour is 60 minutes, a minute is 60 seconds.
- Half an hour is 30 minutes, a quarter of an hour is 15 minutes.
Why it works
With length each step is times ten, but not with time. A century is 100 years, a year 12 months, a week 7 days, a day 24 hours, and an hour and a minute both 60. So an hour is 60 minutes not 100: 0.5 hours is half of 60, so 30 minutes.