Numbers and operations · Ages 12–13

Significant figures worksheet

Part of: Approximation & estimation

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Numbers and operations · Ages 12–13

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

1.0.000373 has significant figures.
Answer:
2.0.001873 correct to 2 significant figures is .
Answer:
3.0.009222 correct to 2 significant figures is .
Answer:
4.897,956 correct to 2 significant figures is .
Answer:
5.0.09409: the first significant figure is ; correct to 2 significant figures it is ; to 3 significant figures, .
Fill in each blank
Answer:
6.616.155 correct to 4 significant figures is .
Answer:

7.Which number has exactly 3 significant figures?
- A. 0.00309
- B. 0.00039
- C. 30.07
- D. 0.3090
Choose the right answer
Answer:
8.0.00221 has 3 significant figures.
True or false?
Answer:
9.What is 0.003065 correct to 3 significant figures?
- A. 0.00306
- B. 0.003
- C. 0.0031
- D. 0.00307
Choose the right answer
Answer:
10.What is 0.002616 correct to 3 significant figures?
- A. 0.00262
- B. 0.003
- C. 0.00261
- D. 0.0026
Choose the right answer
Answer:
11.6.2888 correct to 3 significant figures gives the same answer as correct to 2 decimal places.
True or false?
Answer:
12.5.4393 correct to 3 significant figures gives the same answer as correct to 2 decimal places.
True or false?
Answer:

13.A grain of sand weighs 0.001581 g. Correct to 2 significant figures, how heavy is it?
- A. 0.0015
- B. 0.0016
- C. 0
- D. 0.00158
Choose the right answer
Working:
Answer:
14.A coach travels 506 km in 6 hours. Correct to 3 significant figures, what is its average speed in km/h?
Working:
Answer:
15.A cell is 0.001414 mm long. Correct to 2 significant figures, how long is it?
Working:
Answer:
16.11 cans of soda cost $35. Correct to 3 significant figures, about how much is each can?
Working:
Answer:
17.A city has 5,400,357 people. Correct to 2 significant figures, about how many is that?
Working:
Answer:
18.Chi-keung wrote 175,108 correct to 2 significant figures as 18. Chi-keung is right.
True or false?
Working:
Answer:

Show the answers and working

Significant figures worksheet: Answers and working

1. 3
The zeros in front only place the point; they are not significant. Count from the first digit that isn't 0: 3.
2. 0.0019
The first significant figure is 1; count two, then look at the third, 7: 5 or more rounds up, otherwise it drops. So 0.0019.
3. 0.0092
The first significant figure is 9; count two, then look at the third, 2: 5 or more rounds up, otherwise it drops. So 0.0092.
4. 900,000
Count two significant figures and look at the third, 7; then fill the other places with 0 to keep their values: 900,000, not 90.
5. 9, 0.094, 0.0941
The zeros in front don't count, so the first significant figure is 9. Two figures: 0.094; three: 0.0941.
6. 616.2
The whole-number part already has three significant figures, so the fourth is the first decimal place; look at the second, 5. So 616.2.

7. A. 0.00309
0.00309: the zeros in front don't count. From 3: 3, 0, 9, so 3.
8. True
The 3 zeros in front of 0.00221 only place the point; they are not significant. So 3.
9. D. 0.00307
Count three figures from 3, the first digit that isn't 0, then look at the fourth, 5: it rounds up. So 0.00307.
10. A. 0.00262
Count three figures from 2, the first digit that isn't 0, then look at the fourth, 6: it rounds up. So 0.00262.
11. True
6.2888 to 3 significant figures is 6.29, which has 2 decimal places.
12. True
5.4393 to 3 significant figures is 5.44, which has 2 decimal places.

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

13. B. 0.0016
Count two figures from the first digit that isn't 0 and look at the third, 8: round up. So 0.0016 g.
14. 84.3 km/h
506 ÷ 6 lies between 10 and 100, so 3 significant figures means 1 decimal place: 84.3 km/h.
15. 0.0014 mm
None of the zeros in front is significant; count two figures from the first digit that isn't 0, then look at the next: 0.0014 mm.
16. 3.18 dollars
35 ÷ 11 lies between 1 and 10, so 3 significant figures means 2 decimal places: 3.18 dollars.
17. 5,400,000 people
Count two significant figures, look at the third, and fill the rest with 0 to keep the place values: 5,400,000.
18. False
After rounding, fill the other places with 0 to keep their values: 175,108 is about 180,000, not 18.

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