Numbers and operations · Ages 12–13

Rounding to decimal places worksheet

Part of: Approximation & estimation

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Numbers and operations · Ages 12–13

Numsprite
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Name:Date:Score:／48

Write each answer in the space. For word problems, show your working and write a sentence answer.

1.89.791 correct to 1 decimal place is .
Answer:
2.6.4438 correct to 2 decimal places is .
Answer:
3.5.2806 correct to 2 decimal places is .
Answer:
4.6.90054 correct to 3 decimal places is .
Answer:
5.1.8791 correct to 2 decimal places: the third decimal place is , so the answer is .
Fill in each blank
Answer:
6.1.28839 correct to 3 decimal places is .
Answer:
7.0.06566 correct to the nearest thousandth (3 decimal places) is .
Answer:
8.39.995 correct to 1 decimal place is .
Answer:
9.0.05618 correct to the nearest thousandth (3 decimal places) is .
Answer:

13.Three bags weigh 1.29 kg, 1.88 kg and 9.37 kg. Rounding each to 1 decimal place and then adding, or adding and then rounding to 1 decimal place: how far apart are the two answers?
Working:
Answer:
14.A car uses 6.2 litres of fuel every 100 km. Correct to 1 decimal place, about how many litres does 973 km take?
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15.1 US dollar is 7.82 Hong Kong dollars. Correct to 2 decimal places, about how many US dollars is HK$659?
Working:
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16.Ming ran a stretch in 20.516 seconds and wrote it correct to 2 decimal places as 20.51 seconds. Ming's record is right.
True or false?
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17.A rope 59.3 m long is cut into 6 equal pieces. Correct to 1 decimal place, how long is each piece?
Working:
Answer:
18.Three games scored 91, 91 and 68 points. What is the mean score correct to 1 decimal place?
- A. 83.4
- B. 83.3
- C. 83.33
- D. 83
Choose the right answer
Working:
Answer:

Show the answers and working

Rounding to decimal places worksheet: Answers and working

1. 89.8
Look at the second decimal place, 9: 5 or more rounds up, otherwise it drops. So 89.8.
2. 6.44
Look at the third decimal place, 3: 5 or more rounds up, otherwise it drops, and everything after goes. So 6.44.
3. 5.28
Look at the third decimal place, 0: 5 or more rounds up, otherwise it drops, and everything after goes. So 5.28.
4. 6.901
Look at the fourth decimal place, 5: 5 or more rounds up, otherwise it drops. So 6.901.
5. 9, 1.88
The third decimal place is 9: 5 or more adds 1 to the second, otherwise it stays. So 1.88.
6. 1.288
Look at the fourth decimal place, 3: 5 or more rounds up, otherwise it drops. So 1.288.
7. 0.066
The thousandths are the third decimal place; look at the fourth, 6: 5 or more rounds up, otherwise it drops. So 0.066.
8. 40
The second decimal place is 9, so round up: the 9 and 1 make 10, which carries into the ones. So 40.0, written so to show it is correct to 1 decimal place.
9. 0.056
The thousandths are the third decimal place; look at the fourth, 1: 5 or more rounds up, otherwise it drops. So 0.056.

10. False
The third decimal place is 6, so round up: 41.95. Only cutting the rest off is rounding down, not rounding off.
11. A. 1.5
The arrow is at 1.47. Look at the second decimal place: 5 or more rounds up, otherwise it drops. So 1.5.
12. A. 9.90
The third decimal place, 6, rounds up: 9.89 and 0.01 make 9.90. The answer has 2 decimal places, so the final 0 stays.

Marking: 2 for the working, 1 for the answer, 1 for the sentence.

13. 0.1 kg
Rounding first gives 12.6; adding first gives 12.5. They differ by 0.1: rounding errors add up, so round only at the end.
14. 60.3 litres
6.2 × 973 ÷ 100 = 60.326, which is 60.3 litres to 1 decimal place.
15. 84.27 US dollars
659 ÷ 7.82; look at the third decimal place and round off: 84.27 US dollars.
16. False
The third decimal place is 6, so round up: 20.52 seconds. Only cutting it off is rounding down.
17. 9.9 m
59.3 ÷ 6; look at the second decimal place and round off: 9.9 m.
18. B. 83.3
The mean is 250 ÷ 3, which doesn't come out exactly; the second decimal place is 3, so 83.3.

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