Idea 16of 23Builds onCount the hundredths to each side
Exactly halfway rounds up
What if a number is the same distance from both tenths?
Today you'll discover
- where the halfway mark is
- why distance cannot decide there
- the rule for exactly halfway
Think first56.25 between 56.2 and 56.3
56.25 is exactly halfway between 56.2 and 56.3. Which way does it round?
Decide first, then press Next. Look where the dot sits against the dashed line.
A number line from 56.2 to 56.3 with a dot at 56.25. A dashed line marks halfway: 56.25, right on the dot. Brackets read 5 hundredths each way. Then 56.3 is ringed: 56.25 rounds to 56.3. The last step shows 2.75.
See the whole ideathe big idea and the key word, in one place
The big idea
A number exactly on the halfway mark rounds up, to the greater tenth.
Below, on, past halfway
Between 2.7 and 2.8: 2.74 rounds down to 2.7. 2.75 and 2.76 round up to 2.8.
- 2.742.7
- 2.752.8
- 2.762.8
Easy to get wrongOnly EXACTLY halfway is a tie. 2.74 is 1 hundredth short of halfway, so it is closer to 2.7.
Key word
- halfway mark
- the point exactly between two neighbours: 56.25 between 56.2 and 56.3
Ready to use it?
- Find the halfway mark between two tenths.
- Pick the number that rounds down from three close ones.