Independent practice worksheet for scientific notation addition and subtraction problems.

Let's solve each problem on the Scientific Notation Addition and Subtraction Worksheet step by step.

---

🔧 Key Rule for Adding/Subtracting in Scientific Notation:

To add or subtract numbers in scientific notation, the powers of 10 must be the same. If they are not, adjust one or both numbers so that they have the same exponent, then add/subtract the coefficients.

We’ll convert to the same power of 10, perform the operation, and then express the result in proper scientific notation (i.e., coefficient between 1 and 10).

---

✔ Problem 1: $ 9 \times 10^3 + 2.3 \times 10^4 $

- Convert $ 9 \times 10^3 $ to match $ 10^4 $:
$$
9 \times 10^3 = 0.9 \times 10^4
$$
- Now add:
$$
0.9 \times 10^4 + 2.3 \times 10^4 = (0.9 + 2.3) \times 10^4 = 3.2 \times 10^4
$$

✔ Answer: $ 3.2 \times 10^4 $

---

✔ Problem 2: $ 15 \times 10^2 + 5.2 \times 10^5 $

- First, write $ 15 \times 10^2 $ in proper scientific notation:
$$
15 \times 10^2 = 1.5 \times 10^3
$$
- Now convert $ 1.5 \times 10^3 $ to match $ 10^5 $:
$$
1.5 \times 10^3 = 0.015 \times 10^5
$$
- Add:
$$
0.015 \times 10^5 + 5.2 \times 10^5 = (0.015 + 5.2) \times 10^5 = 5.215 \times 10^5
$$

✔ Answer: $ 5.215 \times 10^5 $

---

✔ Problem 3: $ 10 \times 10^4 + 2.8 \times 10^6 $

- Simplify $ 10 \times 10^4 = 1 \times 10^5 $
- Convert $ 1 \times 10^5 $ to $ 10^6 $:
$$
1 \times 10^5 = 0.1 \times 10^6
$$
- Add:
$$
0.1 \times 10^6 + 2.8 \times 10^6 = (0.1 + 2.8) \times 10^6 = 2.9 \times 10^6
$$

✔ Answer: $ 2.9 \times 10^6 $

---

✔ Problem 4: $ 7 \times 10^3 + 8.6 \times 10^4 $

- Convert $ 7 \times 10^3 $ to $ 10^4 $:
$$
7 \times 10^3 = 0.7 \times 10^4
$$
- Add:
$$
0.7 \times 10^4 + 8.6 \times 10^4 = (0.7 + 8.6) \times 10^4 = 9.3 \times 10^4
$$

✔ Answer: $ 9.3 \times 10^4 $

---

✔ Problem 5: $ 3 \times 10^4 + 14.5 \times 10^5 $

- Convert $ 3 \times 10^4 $ to $ 10^5 $:
$$
3 \times 10^4 = 0.3 \times 10^5
$$
- Add:
$$
0.3 \times 10^5 + 14.5 \times 10^5 = (0.3 + 14.5) \times 10^5 = 14.8 \times 10^5
$$
- Convert to proper scientific notation:
$$
14.8 \times 10^5 = 1.48 \times 10^6
$$

✔ Answer: $ 1.48 \times 10^6 $

---

✔ Problem 6: $ 8 \times 10^4 - 2.7 \times 10^2 $

- Convert $ 2.7 \times 10^2 $ to $ 10^4 $:
$$
2.7 \times 10^2 = 0.027 \times 10^4
$$
- Subtract:
$$
8 \times 10^4 - 0.027 \times 10^4 = (8 - 0.027) \times 10^4 = 7.973 \times 10^4
$$

✔ Answer: $ 7.973 \times 10^4 $

---

✔ Problem 7: $ 5 \times 10^3 - 8.9 \times 10^4 $

- Convert $ 5 \times 10^3 $ to $ 10^4 $:
$$
5 \times 10^3 = 0.5 \times 10^4
$$
- Subtract:
$$
0.5 \times 10^4 - 8.9 \times 10^4 = (0.5 - 8.9) \times 10^4 = -8.4 \times 10^4
$$

✔ Answer: $ -8.4 \times 10^4 $

---

✔ Problem 8: $ 7 \times 10^3 - 8.20 \times 10^2 $

- Convert $ 8.20 \times 10^2 $ to $ 10^3 $:
$$
8.20 \times 10^2 = 0.820 \times 10^3
$$
- Subtract:
$$
7 \times 10^3 - 0.820 \times 10^3 = (7 - 0.820) \times 10^3 = 6.18 \times 10^3
$$

✔ Answer: $ 6.18 \times 10^3 $

---

✔ Problem 9: $ 9 \times 10^2 - 5.54 \times 10^4 $

- Convert $ 9 \times 10^2 $ to $ 10^4 $:
$$
9 \times 10^2 = 0.09 \times 10^4
$$
- Subtract:
$$
0.09 \times 10^4 - 5.54 \times 10^4 = (0.09 - 5.54) \times 10^4 = -5.45 \times 10^4
$$

✔ Answer: $ -5.45 \times 10^4 $

---

✔ Problem 10: $ 10 \times 10^2 - 7.79 \times 10^3 $

- Simplify $ 10 \times 10^2 = 1 \times 10^3 $
- Now subtract:
$$
1 \times 10^3 - 7.79 \times 10^3 = (1 - 7.79) \times 10^3 = -6.79 \times 10^3
$$

✔ Answer: $ -6.79 \times 10^3 $

---

✔ Final Answers:

| Problem | Answer |
|--------|--------|
| 1 | $ 3.2 \times 10^4 $ |
| 2 | $ 5.215 \times 10^5 $ |
| 3 | $ 2.9 \times 10^6 $ |
| 4 | $ 9.3 \times 10^4 $ |
| 5 | $ 1.48 \times 10^6 $ |
| 6 | $ 7.973 \times 10^4 $ |
| 7 | $ -8.4 \times 10^4 $ |
| 8 | $ 6.18 \times 10^3 $ |
| 9 | $ -5.45 \times 10^4 $ |
| 10 | $ -6.79 \times 10^3 $ |

---

📌 Summary Tips:

- Always align exponents before adding or subtracting.
- Use decimal shifting to convert numbers to the same power of 10.
- After computing, ensure your final answer is in proper scientific notation (coefficient ≥ 1 and < 10).
- Be careful with signs when subtracting.

Let me know if you'd like a printable version or want these problems explained in video format!