Idea 20of 23Builds onRounding picks the closer tenth
Rounding measurements in real life
Why would you round a length, a mass or a time?
Today you'll discover
- how to round a trail's length
- how a race time is rounded
- that the rule is the same for every unit
Think firstA trail 4.36 km long
A trail is 4.36 km long. About how long is it, to the nearest tenth of a kilometre?
Decide first, then press Next. The unit stays the same; only the number is rounded.
A number line from 4.3 to 4.4 captioned a trail's length in kilometres, with a dot at 4.36 km rounding to 4.4 km. Then a race time of 15.47 s rounding to 15.5 s, and a pumpkin of 3.82 kg rounding to 3.8 kg. The last step shows a backpack of 5.38 kg.
See the whole ideathe big idea and the key word, in one place
The big idea
A rounded measurement is a quick, close estimate: 4.36 km is about 4.4 km.
Every unit, one rule
A trail of 4.36 km is about 4.4 km. A race of 15.47 s is about 15.5 s. A pumpkin of 3.82 kg is about 3.8 kg.
- 4.36 km4.4 km
- 15.47 s15.5 s
- 3.82 kg3.8 kg
Where it goes nextRounded numbers are easy to add in your head, to check whether an exact answer makes sense.
Key word
- estimate
- a number close to the exact one, good enough for the job
Ready to use it?
- Round a length, mass or time to the nearest tenth.
- Say a measurement with “about”.