Lesson 8 of 14
Round which way?
Show on a big screenPaper cups come in packs of 10. You need one cup for each of 143 children. How many packs do you buy?
Step 1 of 4
- Packs hold 10. There are 143 children.
- Down to 140. Three children get no cup.
- Up to 150. Seven cups are spare.
- Here, spare is better than short.
15 packs give 150 cups. That is enough for 143 children.
The rule
The nearest ten is 140. But 140 cups are not enough for 143 children. So 140 is not the best answer here. What you need decides whether to round up or down.
Round up when you need enough. Round down when you must not go over. Keep the exact number when it has to match.
| You need | Way | Example |
|---|---|---|
| Enough | Up | 143 children, packs of 10: buy 150 |
| Not to go over | Down | You have ₹3,740. The shop takes only ₹500 notes: pay ₹3,500 |
| A match | Exact | Room number 417 stays 417 |
Sometimes up and down are both fine. A stadium sells 48,213 tickets. A news report may say about 48,000.
Tap the number that fits each situation in the lab.
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Try the lab to finish this lesson.