Significant Figures (Sig Figs): Practice Questions and Answer Key

Questions: Significant Figures (Sig Figs)

Understanding significant figures is essential for scientific measurements, chemistry calculations, and laboratory accuracy. As a Science Teacher and Education Specialist, I have worked with students to develop precision and analytical skills through practical chemistry exercises. This collection of Significant Figures (Sig Figs) questions with answer key helps learners apply measurement rules, improve quantitative reasoning, and strengthen their understanding of scientific data used in chemistry, physics, engineering, and laboratory investigations.



Multiple-choice questions (with five alternatives each) covering:

    • Significant Figures (Sig Figs)

    • Significant Figures in Addition and Subtraction

    • Significant Figures in Multiplication and Division

Answers with detailed explanations are provided at the end.


 Multiple-Choice Questions: Significant Figures


General Concepts – Significant Figures

    1. How many significant figures are in the number 0.00560?

A) 5

B) 4

C) 3

D) 2

E) 1

    2. Which of the following numbers has 4 significant figures?

A) 0.00456

B) 4560

C) 4.560

D) 456000

E) 45.6

    3. Which zeros are considered significant?

A) Leading zeros only

B) Captive (between non-zero digits) and trailing zeros after decimal

C) Only trailing zeros before decimal

D) Leading and trailing zeros

E) No zeros are ever significant

    4. How many significant figures are in 300.0?

A) 1

B) 2

C) 3

D) 4

E) 5

    5. Which number has only 1 significant figure?

A) 0.010

B) 1.0

C) 0.1

D) 10.0

E) 0.0100

    6. In scientific notation, how many significant figures does 3.20 × 10⁴ have?

A) 1

B) 2

C) 3

D) 4

E) 5

    7. What is the number of significant figures in 0.000300?

A) 1

B) 2

C) 3

D) 4

E) 5

    8. Which number below is written with 5 significant figures?

A) 0.00056

B) 1.2345

C) 123.45

D) 100.0

E) 56.7

    9. Which of the following numbers has no significant figures?

A) 0.0

B) 0.00400

C) 0

D) 0.01

E) 0.05

    10. How many significant figures are in the number 7.090?

A) 2

B) 3

C) 4

D) 5

E) 6


Addition and Subtraction with Sig Figs

    11. What rule governs significant figures in addition and subtraction?

A) Round to the fewest number of significant figures

B) Round to the most decimal places

C) Round to the least number of decimal places

D) Ignore all decimals

E) Use scientific notation

    12. Calculate: 12.11 + 18.0 + 1.013 (rounded correctly)

A) 31.123

B) 31.12

C) 31.1

D) 31.0

E) 30

    13. Perform: 123.45 − 23.1, using correct sig figs

A) 100.35

B) 100.3

C) 100

D) 100.4

E) 99

    14. Which result has the correct number of sig figs: 45.60 − 5.2

A) 40.4

B) 40.40

C) 40

D) 40.400

E) 40.5

    15. If 8.990 + 2.1 is calculated, the answer should be rounded to:

A) 11.09

B) 11.1

C) 11.090

D) 11.0

E) 12


Multiplication and Division with Sig Figs

    16. What is the rule for sig figs in multiplication and division?

A) Round to the most decimal places

B) Use scientific notation

C) Round to the fewest significant figures

D) Ignore zeros

E) Always round to 3 sig figs

    17. Calculate: 4.56 × 1.4, with correct sig figs

A) 6.38

B) 6.4

C) 6.384

D) 6

E) 7

    18. Perform: 12.0 ÷ 3.00, using sig figs

A) 4

B) 4.00

C) 4.0

D) 3.9

E) 5.00

    19. Find the result of: 6.022 × 0.20

A) 1.204

B) 1.2

C) 1.2044

D) 1.20

E) 1

    20. Calculate: 100.0 × 3.00, properly rounded

A) 300

B) 300.0

C) 300.00

D) 3.0

E) 30

    21. How many significant figures are in the result of 25.0 ÷ 2.50?

A) 1

B) 2

C) 3

D) 4

E) 5

    22. If you multiply 0.020 × 10.0, what is the result with correct sig figs?

A) 0.2

B) 0.200

C) 0.20

D) 2

E) 0.02

    23. Calculate: 9.876 × 1.2 using correct sig figs

A) 11.8512

B) 11.9

C) 11.85

D) 12

E) 10

    24. Which answer is correct for 8.00 ÷ 4.000?

A) 2

B) 2.0

C) 2.00

D) 2.000

E) 2.5

    25. In multiplication/division, zeros before digits are:

A) Always significant

B) Never significant

C) Sometimes significant

D) Counted as 1 sig fig

E) Doubled

    26. Calculate 3.00 × 0.00400 and give the sig figs

A) 0.0120

B) 0.012

C) 0.01200

D) 0.01

E) 0.012000

    27. In the operation 2.50 × 4.0 ÷ 1.00, how many sig figs should the answer have?

A) 1

B) 2

C) 3

D) 4

E) 5

    28. What is the product of 5.678 × 2.0, rounded?

A) 11.4

B) 11.36

C) 11.356

D) 11

E) 10

    29. A value of 6.02 × 10²³ has how many significant figures?

A) 1

B) 2

C) 3

D) 4

E) Infinite

    30. How many significant figures are in the result of 1.000 × 0.0001?

A) 1

B) 2

C) 3

D) 4

E) 5



Significant Figures (Sig Figs): Practice Questions and Answer Key

 Answer Key with Explanations

    1. C – 3 sig figs: 5, 6, and trailing zero

    2. C – 4 sig figs (trailing zero is after a decimal)

    3. B – Captive and trailing after decimal are significant

    4. D – All digits including the zero are significant

    5. C – Only the "1" is significant

    6. C – All digits in mantissa count as sig figs

    7. C – 3 sig figs: 3, 0, and trailing 0

    8. B – 1.2345 has 5 sig figs

    9. C – 0 alone has no significant figures

    10. C – 7, 0, 9, and final 0 are all significant

    11. C – Round to least decimal places

    12. C – Least decimals = 1 (from 18.0), answer is 31.1

    13. B – Final answer must have 1 decimal (from 23.1)

    14. A – 1 decimal place: 40.4

    15. B – One decimal: 11.1

    16. C – Round to least number of sig figs

    17. B – 2 sig figs (from 1.4): 6.4

    18. C – 3 sig figs (12.0 and 3.00): 4.00

    19. D – 2 sig figs (from 0.20): 1.20

    20. B – 3 sig figs total: 300.0

    21. C – Each has 3 sig figs → result has 3 sig figs

    22. C – 2 sig figs: 0.020 has 2, 10.0 has 3 → result: 0.20

    23. B – 2 sig figs (from 1.2): 11.9

    24. C – Least sig figs = 3 → 2.00

    25. B – Zeros before digits are not significant

    26. A – 3 sig figs: result is 0.0120

    27. B – Least sig figs = 2 (from 4.0)

    28. A – 2 sig figs → round to 11.4

    29. C – 6.02 has 3 sig figs

    30. D – Final answer has 4 sig figs

Practical Classroom Applications

Teachers can use this topic in several ways to increase student engagement and reinforce scientific reasoning:
    • Measurement Laboratory Activities 
        ◦ Students record measurements using rulers, balances, and graduated cylinders while applying significant figure rules. 
    • Chemistry Calculations Practice 
        ◦ Integrate sig figs into density, molarity, and stoichiometry calculations. 
    • Scientific Notation Exercises 
        ◦ Connect significant figures with powers of ten and scientific notation. 
    • Precision vs. Accuracy Discussions 
        ◦ Analyze the difference between accurate measurements and precise measurements. 
    • Experimental Error Analysis 
        ◦ Evaluate how measurement uncertainty affects scientific results. 
    • Engineering and STEM Applications 
        ◦ Demonstrate how engineers and scientists rely on precise numerical reporting. 
    • Physics Measurement Activities 
        ◦ Apply significant figures to velocity, force, and density calculations. 
    • Data Interpretation Projects 
        ◦ Compare experimental datasets and determine appropriate reporting precision. 
    • Calculator and Rounding Exercises 
        ◦ Practice addition, subtraction, multiplication, and division using sig fig rules. 
    • Real-World Scenarios 
        ◦ Explore applications in medicine, environmental science, manufacturing, and analytical chemistry.

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Ronaldo Silva: Professor and Specialist in Science Education from University Federal FLuminense/RJ, with over 25 years of teaching experience..

 
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