Idea 21of 23Builds onRounding measurements in real life
Round up to have enough
Is the nearest tenth always the best choice?
Today you'll discover
- when the nearest tenth falls short
- why you sometimes round up on purpose
- how to pick the shortest length that works
Think firstA banner needs 2.43 m of ribbon
A banner needs 2.43 m of ribbon. Is 2.4 m of ribbon enough?
Decide first, then press Next. Ask whether the rounded length still covers the need.
A number line from 2.4 to 2.5 captioned ribbon needed for a banner, in metres, with a dot at 2.43 m. 2.4 m is ringed as the nearest tenth, then an orange line reads 2.4 m is not enough: take 2.5 m, and 2.5 m is ringed. Then paint: 0.62 L, take 0.7 L. The last step shows a shelf that needs 1.32 m.
See the whole ideathe big idea and the key word, in one place
The big idea
When you must have enough, round up to the next tenth, even if the lower tenth is closer.
Nearest or enough?
2.43 m to the nearest tenth is 2.4 m. Enough ribbon for 2.43 m is 2.5 m.
- Nearest tenth2.4 m
- Enough2.5 m
Easy to get wrongUse this only when the story needs it. To say about how long something is, round to the nearest tenth as usual.
Key word
- overestimate
- an estimate a little more than the exact amount, chosen so you do not run short
Ready to use it?
- Decide whether a story needs the nearest tenth or the next tenth up.
- Pick the shortest length that is enough.