Printable worksheet for practicing significant figures in addition and subtraction.
Worksheet titled "Significant Figures: Addition and Subtraction" with 20 math problems requiring rounding to the correct number of significant figures.
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Step-by-step solution for: Significant Figures Worksheet PDF - Addition Practice
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Show Answer Key & Explanations
Step-by-step solution for: Significant Figures Worksheet PDF - Addition Practice
Let's solve each problem in the worksheet step by step, applying the rules for significant figures in addition and subtraction.
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When adding or subtracting numbers, the result should be rounded to the least precise decimal place (i.e., the number with the fewest decimal places).
For example:
- If you add 35.6 (1 decimal) and 56.27 (2 decimals), the answer must be rounded to 1 decimal place.
---
Now, let’s go through each problem:
---
- $ 35.6 + 56.27 = 91.87 $
- 35.6 has 1 decimal, 56.27 has 2 decimals
- Round to 1 decimal place:
→ 91.9
✔ Answer: 91.9
---
- $ 4.337 + 84.7128 = 89.0498 $
- 4.337 has 3 decimals, 84.7128 has 4 decimals
- Round to 3 decimal places:
→ 89.050
✔ Answer: 89.050
---
- $ 6.2 + 4.114 = 10.314 $
- 6.2 has 1 decimal, 4.114 has 3 decimals
- Round to 1 decimal place:
→ 10.3
✔ Answer: 10.3
---
- $ 7.331 + 12.42 = 19.751 $
- 7.331 has 3 decimals, 12.42 has 2 decimals
- Round to 2 decimal places:
→ 19.75
✔ Answer: 19.75
---
- $ 22.5285 + 22.14 = 44.6685 $
- $ 44.6685 + 4.266 = 48.9345 $
- Now check decimal places:
- 22.5285 → 4 decimals
- 22.14 → 2 decimals
- 4.266 → 3 decimals
- Least precise is 2 decimals
- Round to 2 decimal places:
→ 48.93
✔ Answer: 48.93
---
- $ 88.489 + 7.133 = 95.622 $
- $ 95.622 + 6.5 = 102.122 $
- Decimal places:
- 88.489 → 3
- 7.133 → 3
- 6.5 → 1
- Least precise is 1 decimal
- Round to 1 decimal place:
→ 102.1
✔ Answer: 102.1
---
- $ 48.835 - 9.1 = 39.735 $
- 48.835 → 3 decimals, 9.1 → 1 decimal
- Round to 1 decimal place:
→ 39.7
✔ Answer: 39.7
---
- $ 16.221 - 8.28 = 7.941 $
- 16.221 → 3 decimals, 8.28 → 2 decimals
- Round to 2 decimal places:
→ 7.94
✔ Answer: 7.94
---
- $ 101.12 - 98.7 = 2.42 $
- 101.12 → 2 decimals, 98.7 → 1 decimal
- Round to 1 decimal place:
→ 2.4
✔ Answer: 2.4
---
- $ 13.7 + 25.466 = 39.166 $
- 13.7 → 1 decimal, 25.466 → 3 decimals
- Round to 1 decimal place:
→ 39.2
✔ Answer: 39.2
---
- $ 45.758 - 33.22 = 12.538 $
- 45.758 → 3 decimals, 33.22 → 2 decimals
- Round to 2 decimal places:
→ 12.54
✔ Answer: 12.54
---
- $ 19.6 - 8.77 = 10.83 $
- 19.6 → 1 decimal, 8.77 → 2 decimals
- Round to 1 decimal place:
→ 10.8
✔ Answer: 10.8
---
- $ 23 + 16.4 = 39.4 $
- $ 39.4 + 22.0 = 61.4 $
- Decimal places:
- 23 → no decimal (whole number)
- 16.4 → 1 decimal
- 22.0 → 1 decimal
- The least precise is no decimal (23 is exact to the ones place)
- So round to nearest whole number:
- 61.4 → 61
✔ Answer: 61
---
- $ 24.5764 - 1.9833 = 22.5931 $
- Both have 4 decimals
- Round to 4 decimal places:
→ 22.5931
✔ Answer: 22.5931
---
- $ 8.31 + 7.2 = 15.51 $
- $ 15.51 + 9.4626 = 24.9726 $
- Decimal places:
- 8.31 → 2
- 7.2 → 1
- 9.4626 → 4
- Least precise: 1 decimal
- Round to 1 decimal place:
→ 25.0
✔ Answer: 25.0
---
- $ 3.94 + 68.77 = 72.71 $
- $ 72.71 + 83.197 = 155.907 $
- Decimal places:
- 3.94 → 2
- 68.77 → 2
- 83.197 → 3
- Least precise: 2 decimals
- Round to 2 decimal places:
→ 155.91
✔ Answer: 155.91
---
- $ 12.484 + 3.6 = 16.084 $
- 12.484 → 3 decimals, 3.6 → 1 decimal
- Round to 1 decimal place:
→ 16.1
✔ Answer: 16.1
---
- $ 19.117 - 8.11 = 11.007 $
- 19.117 → 3 decimals, 8.11 → 2 decimals
- Round to 2 decimal places:
→ 11.01
✔ Answer: 11.01
---
- First: $ 7.6924 + 9.6 = 17.2924 $
- Then: $ 17.2924 - 4.888 = 12.4044 $
- Check precision:
- 7.6924 → 4 decimals
- 9.6 → 1 decimal
- 4.888 → 3 decimals
- Least precise is 1 decimal
- Round to 1 decimal place:
→ 12.4
✔ Answer: 12.4
---
- First: $ 19.8 - 8.75 = 11.05 $
- Then: $ 11.05 + 11 = 22.05 $
- Precision:
- 19.8 → 1 decimal
- 8.75 → 2 decimals
- 11 → no decimal
- The least precise is 11 (whole number), so round to nearest whole number
- 22.05 → 22
✔ Answer: 22
---
## ✔ Final Answers:
| # | Problem | Answer |
|---|--------|--------|
| 1 | 35.6 + 56.27 | 91.9 |
| 2 | 4.337 + 84.7128 | 89.050 |
| 3 | 6.2 + 4.114 | 10.3 |
| 4 | 7.331 + 12.42 | 19.75 |
| 5 | 22.5285 + 22.14 + 4.266 | 48.93 |
| 6 | 88.489 + 7.133 + 6.5 | 102.1 |
| 7 | 48.835 - 9.1 | 39.7 |
| 8 | 16.221 - 8.28 | 7.94 |
| 9 | 101.12 - 98.7 | 2.4 |
|10 | 13.7 + 25.466 | 39.2 |
|11 | 45.758 - 33.22 | 12.54 |
|12 | 19.6 - 8.77 | 10.8 |
|13 | 23 + 16.4 + 22.0 | 61 |
|14 | 24.5764 - 1.9833 | 22.5931 |
|15 | 8.31 + 7.2 + 9.4626 | 25.0 |
|16 | 3.94 + 68.77 + 83.197 | 155.91 |
|17 | 12.484 + 3.6 | 16.1 |
|18 | 19.117 - 8.11 | 11.01 |
|19 | 7.6924 + 9.6 - 4.888 | 12.4 |
|20 | 19.8 - 8.75 + 11 | 22 |
---
Let me know if you'd like this as a printable PDF or need help with multiplication/division significant figures next!
---
🔷 Rule for Addition and Subtraction:
When adding or subtracting numbers, the result should be rounded to the least precise decimal place (i.e., the number with the fewest decimal places).
For example:
- If you add 35.6 (1 decimal) and 56.27 (2 decimals), the answer must be rounded to 1 decimal place.
---
Now, let’s go through each problem:
---
1. $ 35.6 + 56.27 $
- $ 35.6 + 56.27 = 91.87 $
- 35.6 has 1 decimal, 56.27 has 2 decimals
- Round to 1 decimal place:
→ 91.9
✔ Answer: 91.9
---
2. $ 4.337 + 84.7128 $
- $ 4.337 + 84.7128 = 89.0498 $
- 4.337 has 3 decimals, 84.7128 has 4 decimals
- Round to 3 decimal places:
→ 89.050
✔ Answer: 89.050
---
3. $ 6.2 + 4.114 $
- $ 6.2 + 4.114 = 10.314 $
- 6.2 has 1 decimal, 4.114 has 3 decimals
- Round to 1 decimal place:
→ 10.3
✔ Answer: 10.3
---
4. $ 7.331 + 12.42 $
- $ 7.331 + 12.42 = 19.751 $
- 7.331 has 3 decimals, 12.42 has 2 decimals
- Round to 2 decimal places:
→ 19.75
✔ Answer: 19.75
---
5. $ 22.5285 + 22.14 + 4.266 $
- $ 22.5285 + 22.14 = 44.6685 $
- $ 44.6685 + 4.266 = 48.9345 $
- Now check decimal places:
- 22.5285 → 4 decimals
- 22.14 → 2 decimals
- 4.266 → 3 decimals
- Least precise is 2 decimals
- Round to 2 decimal places:
→ 48.93
✔ Answer: 48.93
---
6. $ 88.489 + 7.133 + 6.5 $
- $ 88.489 + 7.133 = 95.622 $
- $ 95.622 + 6.5 = 102.122 $
- Decimal places:
- 88.489 → 3
- 7.133 → 3
- 6.5 → 1
- Least precise is 1 decimal
- Round to 1 decimal place:
→ 102.1
✔ Answer: 102.1
---
7. $ 48.835 - 9.1 $
- $ 48.835 - 9.1 = 39.735 $
- 48.835 → 3 decimals, 9.1 → 1 decimal
- Round to 1 decimal place:
→ 39.7
✔ Answer: 39.7
---
8. $ 16.221 - 8.28 $
- $ 16.221 - 8.28 = 7.941 $
- 16.221 → 3 decimals, 8.28 → 2 decimals
- Round to 2 decimal places:
→ 7.94
✔ Answer: 7.94
---
9. $ 101.12 - 98.7 $
- $ 101.12 - 98.7 = 2.42 $
- 101.12 → 2 decimals, 98.7 → 1 decimal
- Round to 1 decimal place:
→ 2.4
✔ Answer: 2.4
---
10. $ 13.7 + 25.466 $
- $ 13.7 + 25.466 = 39.166 $
- 13.7 → 1 decimal, 25.466 → 3 decimals
- Round to 1 decimal place:
→ 39.2
✔ Answer: 39.2
---
11. $ 45.758 - 33.22 $
- $ 45.758 - 33.22 = 12.538 $
- 45.758 → 3 decimals, 33.22 → 2 decimals
- Round to 2 decimal places:
→ 12.54
✔ Answer: 12.54
---
12. $ 19.6 - 8.77 $
- $ 19.6 - 8.77 = 10.83 $
- 19.6 → 1 decimal, 8.77 → 2 decimals
- Round to 1 decimal place:
→ 10.8
✔ Answer: 10.8
---
13. $ 23 + 16.4 + 22.0 $
- $ 23 + 16.4 = 39.4 $
- $ 39.4 + 22.0 = 61.4 $
- Decimal places:
- 23 → no decimal (whole number)
- 16.4 → 1 decimal
- 22.0 → 1 decimal
- The least precise is no decimal (23 is exact to the ones place)
- So round to nearest whole number:
- 61.4 → 61
✔ Answer: 61
---
14. $ 24.5764 - 1.9833 $
- $ 24.5764 - 1.9833 = 22.5931 $
- Both have 4 decimals
- Round to 4 decimal places:
→ 22.5931
✔ Answer: 22.5931
---
15. $ 8.31 + 7.2 + 9.4626 $
- $ 8.31 + 7.2 = 15.51 $
- $ 15.51 + 9.4626 = 24.9726 $
- Decimal places:
- 8.31 → 2
- 7.2 → 1
- 9.4626 → 4
- Least precise: 1 decimal
- Round to 1 decimal place:
→ 25.0
✔ Answer: 25.0
---
16. $ 3.94 + 68.77 + 83.197 $
- $ 3.94 + 68.77 = 72.71 $
- $ 72.71 + 83.197 = 155.907 $
- Decimal places:
- 3.94 → 2
- 68.77 → 2
- 83.197 → 3
- Least precise: 2 decimals
- Round to 2 decimal places:
→ 155.91
✔ Answer: 155.91
---
17. $ 12.484 + 3.6 $
- $ 12.484 + 3.6 = 16.084 $
- 12.484 → 3 decimals, 3.6 → 1 decimal
- Round to 1 decimal place:
→ 16.1
✔ Answer: 16.1
---
18. $ 19.117 - 8.11 $
- $ 19.117 - 8.11 = 11.007 $
- 19.117 → 3 decimals, 8.11 → 2 decimals
- Round to 2 decimal places:
→ 11.01
✔ Answer: 11.01
---
19. $ 7.6924 + 9.6 - 4.888 $
- First: $ 7.6924 + 9.6 = 17.2924 $
- Then: $ 17.2924 - 4.888 = 12.4044 $
- Check precision:
- 7.6924 → 4 decimals
- 9.6 → 1 decimal
- 4.888 → 3 decimals
- Least precise is 1 decimal
- Round to 1 decimal place:
→ 12.4
✔ Answer: 12.4
---
20. $ 19.8 - 8.75 + 11 $
- First: $ 19.8 - 8.75 = 11.05 $
- Then: $ 11.05 + 11 = 22.05 $
- Precision:
- 19.8 → 1 decimal
- 8.75 → 2 decimals
- 11 → no decimal
- The least precise is 11 (whole number), so round to nearest whole number
- 22.05 → 22
✔ Answer: 22
---
## ✔ Final Answers:
| # | Problem | Answer |
|---|--------|--------|
| 1 | 35.6 + 56.27 | 91.9 |
| 2 | 4.337 + 84.7128 | 89.050 |
| 3 | 6.2 + 4.114 | 10.3 |
| 4 | 7.331 + 12.42 | 19.75 |
| 5 | 22.5285 + 22.14 + 4.266 | 48.93 |
| 6 | 88.489 + 7.133 + 6.5 | 102.1 |
| 7 | 48.835 - 9.1 | 39.7 |
| 8 | 16.221 - 8.28 | 7.94 |
| 9 | 101.12 - 98.7 | 2.4 |
|10 | 13.7 + 25.466 | 39.2 |
|11 | 45.758 - 33.22 | 12.54 |
|12 | 19.6 - 8.77 | 10.8 |
|13 | 23 + 16.4 + 22.0 | 61 |
|14 | 24.5764 - 1.9833 | 22.5931 |
|15 | 8.31 + 7.2 + 9.4626 | 25.0 |
|16 | 3.94 + 68.77 + 83.197 | 155.91 |
|17 | 12.484 + 3.6 | 16.1 |
|18 | 19.117 - 8.11 | 11.01 |
|19 | 7.6924 + 9.6 - 4.888 | 12.4 |
|20 | 19.8 - 8.75 + 11 | 22 |
---
Let me know if you'd like this as a printable PDF or need help with multiplication/division significant figures next!
Parent Tip: Review the logic above to help your child master the concept of sig figs worksheet.
