Use this printable worksheet to practice identifying the number of significant figures in a variety of numerical formats.

Let's solve each of these problems step by step using the rules for significant figures:

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🔢 Rules for Significant Figures:

1. All non-zero digits are significant.
2. Zeros between non-zero digits are significant.
3. Leading zeros (before the first non-zero digit) are NOT significant.
4. Trailing zeros (after the last non-zero digit) are significant ONLY if the number has a decimal point.
5. In scientific notation, only the digits in the coefficient are considered; the exponent does not affect significance.
6. Exact numbers (like counts or defined values) have infinite significant figures, but here we're dealing with measurements.

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Now let’s go through each number:

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1. 357

- All digits are non-zero → 3 significant figures

✔ Answer: 3

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2. 10000

- No decimal point → trailing zeros are not significant
- Only the '1' is significant
- So, 1 significant figure

✔ Answer: 1

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3. 51015

- All digits are non-zero → all are significant
- 5 digits total

✔ Answer: 5

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4. 6.060 × 10⁻²

- Coefficient is 6.060
- Zeros between and after non-zero digits are significant
- 6, 0, 6, 0 → all four digits are significant

✔ Answer: 4

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5. 0.0007

- Leading zeros are not significant
- Only the '7' is significant

✔ Answer: 1

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6. 4.556 × 10⁻⁹

- Coefficient is 4.556 → all digits are significant
- 4 digits

✔ Answer: 4

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7. 5050

- No decimal point → trailing zero is not significant
- The middle zero is between non-zero digits → significant
- So: 5, 0, 5 → three significant figures (last zero is not significant)

✔ Answer: 3

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8. 5050.0

- Has a decimal point → trailing zero is significant
- So: 5, 0, 5, 0, 0 → all five digits are significant

✔ Answer: 5

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9. 6.8 × 10³

- Coefficient: 6.8 → two digits
- Both are significant

✔ Answer: 2

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10. 0.002110

- Leading zeros: not significant
- First non-zero digit: 2
- Then 1, 1, 0 → the last zero is after the decimal and after non-zero digits → significant
- So: 2, 1, 1, 0 → 4 significant figures

✔ Answer: 4

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11. 33.303

- All digits are non-zero except one zero in the middle
- Zero is between non-zero digits → significant
- Total: 5 digits

✔ Answer: 5

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12. 170

- No decimal point → trailing zero is not significant
- So only 1 and 7 are significant → 2 significant figures

✔ Answer: 2

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13. 15.0 × 10⁻⁵

- Coefficient: 15.0 → the zero after the decimal is significant
- So: 1, 5, 0 → 3 significant figures

✔ Answer: 3

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14. 0.7007

- Leading zero: not significant
- 7, 0, 0, 7 → zeros are between non-zero digits → significant
- So all four digits are significant

✔ Answer: 4

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15. 0.70070

- Leading zero: not significant
- Digits: 7, 0, 0, 7, 0 → last zero is after decimal and after non-zero → significant
- So: 5 significant figures

✔ Answer: 5

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16. 4206

- All digits are non-zero → all are significant
- 4 digits

✔ Answer: 4

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17. 0.02

- Leading zeros: not significant
- Only the '2' is significant

✔ Answer: 1

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18. 10.01

- All digits are significant
- The zeros are between non-zero digits → significant
- 1, 0, 0, 1 → 4 significant figures

✔ Answer: 4

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19. 0

- This is just zero with no context
- In measurement, zero alone has no significant figures unless specified otherwise
- But technically, 0 has 1 significant figure in some contexts — however, in most scientific conventions, a standalone zero has no significant figures.
- But in this case, since it's written as "0", it's ambiguous.

However, standard rule:
> A number like 0 (without decimal) has no significant figures because it's an exact value or undefined precision.

But sometimes, 0 is considered to have 1 significant figure.

To be safe:
➡️ Most sources say that "0" has 1 significant figure when it's a measured value, but if it's just a placeholder, it may not count.

But in this context, since it's listed as "0", and not "0.0" or "0.00", it's likely intended to be 1 significant figure.

But wait — actually, if it's just "0", it's not a measurement, so it has no significant figures.

However, common practice in such worksheets treats 0 as having 1 significant figure.

Let’s check logic:
- 0.0 → 1 sig fig? No — usually not.
- But "0" is ambiguous.

But based on common textbook treatment:
👉 "0" is considered to have 1 significant figure.

✔ Answer: 1

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20. 0.0

- Written as 0.0 → has a decimal point
- The zero after decimal is significant? Yes, because it indicates precision
- So: 0.0 → 1 significant figure

✔ Answer: 1

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✔ Final Answers:

| Number | Significant Figures |
|--------|---------------------|
| 1. 357 | 3 |
| 2. 10000 | 1 |
| 3. 51015 | 5 |
| 4. 6.060 × 10⁻² | 4 |
| 5. 0.0007 | 1 |
| 6. 4.556 × 10⁻⁹ | 4 |
| 7. 5050 | 3 |
| 8. 5050.0 | 5 |
| 9. 6.8 × 10³ | 2 |
| 10. 0.002110 | 4 |
| 11. 33.303 | 5 |
| 12. 170 | 2 |
| 13. 15.0 × 10⁻⁵ | 3 |
| 14. 0.7007 | 4 |
| 15. 0.70070 | 5 |
| 16. 4206 | 4 |
| 17. 0.02 | 1 |
| 18. 10.01 | 4 |
| 19. 0 | 1 |
| 20. 0.0 | 1 |

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📌 Summary Table:

```
1. 3
2. 1
3. 5
4. 4
5. 1
6. 4
7. 3
8. 5
9. 2
10. 4
11. 5
12. 2
13. 3
14. 4
15. 5
16. 4
17. 1
18. 4
19. 1
20. 1
```

Let me know if you want this filled into the worksheet format!