Let's solve each problem step by step, following the method shown in the examples. The key idea is to
rewrite both numbers so they have the same power of 10, then add or subtract the coefficients. After that, express the result in proper scientific notation (i.e., a number between 1 and 10 multiplied by a power of 10).
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Problem 1:
(2 × 10³) + (5 × 10⁵)
We need the same exponent. Let’s convert both to have
10⁵.
- 2 × 10³ = 0.02 × 10⁵
- So: (0.02 × 10⁵) + (5 × 10⁵) = (0.02 + 5) × 10⁵ = 5.02 × 10⁵
✔ Answer: 5.02 × 10⁵
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Problem 2:
(4 × 10⁸) – (9 × 10⁷)
Convert both to have
10⁸:
- 9 × 10⁷ = 0.9 × 10⁸
- So: (4 × 10⁸) – (0.9 × 10⁸) = (4 – 0.9) × 10⁸ = 3.1 × 10⁸
✔ Answer: 3.1 × 10⁸
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Problem 3:
(8 × 10⁹) – (3 × 10⁷)
Convert both to
10⁹:
- 3 × 10⁷ = 0.03 × 10⁹
- So: (8 × 10⁹) – (0.03 × 10⁹) = (8 – 0.03) × 10⁹ = 7.97 × 10⁹
✔ Answer: 7.97 × 10⁹
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Problem 4:
(5 × 10⁷) + (1 × 10⁶)
Convert both to
10⁷:
- 1 × 10⁶ = 0.1 × 10⁷
- So: (5 × 10⁷) + (0.1 × 10⁷) = (5 + 0.1) × 10⁷ = 5.1 × 10⁷
✔ Answer: 5.1 × 10⁷
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Problem 5:
(4 × 10²) + (7 × 10³)
Convert both to
10³:
- 4 × 10² = 0.4 × 10³
- So: (0.4 × 10³) + (7 × 10³) = (0.4 + 7) × 10³ = 7.4 × 10³
✔ Answer: 7.4 × 10³
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Problem 6:
(9 × 10⁵) – (6 × 10⁴)
Convert both to
10⁵:
- 6 × 10⁴ = 0.6 × 10⁵
- So: (9 × 10⁵) – (0.6 × 10⁵) = (9 – 0.6) × 10⁵ = 8.4 × 10⁵
✔ Answer: 8.4 × 10⁵
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Problem 7:
(1 × 10⁶) – (8 × 10⁴)
Convert both to
10⁶:
- 8 × 10⁴ = 0.08 × 10⁶
- So: (1 × 10⁶) – (0.08 × 10⁶) = (1 – 0.08) × 10⁶ = 0.92 × 10⁶
But this is
not in proper scientific notation (0.92 < 1). We fix it:
- 0.92 × 10⁶ = 9.2 × 10⁵
✔ Answer: 9.2 × 10⁵
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Problem 8:
(5 × 10⁹) + (3 × 10⁸)
Convert both to
10⁹:
- 3 × 10⁸ = 0.3 × 10⁹
- So: (5 × 10⁹) + (0.3 × 10⁹) = (5 + 0.3) × 10⁹ = 5.3 × 10⁹
✔ Answer: 5.3 × 10⁹
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✔ Final Answers:
| Problem | Answer |
|--------|--------|
| 1) |
5.02 × 10⁵ |
| 2) |
3.1 × 10⁸ |
| 3) |
7.97 × 10⁹ |
| 4) |
5.1 × 10⁷ |
| 5) |
7.4 × 10³ |
| 6) |
8.4 × 10⁵ |
| 7) |
9.2 × 10⁵ |
| 8) |
5.3 × 10⁹ |
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🔍 Summary of Strategy:
1. Make exponents the same by adjusting the decimal.
2. Add or subtract the coefficients.
3. Write result in standard scientific notation (coefficient between 1 and 10).
Let me know if you'd like a printable version or explanation for any specific step!
Parent Tip: Review the logic above to help your child master the concept of scientific notation addition and subtraction worksheet.