Prime and Composite numbers -week 9 (grade 5) - Super Teacher ... - Free Printable

Absolutely! Let's solve the worksheet step by step. The goal is to list all factors of each given number and then classify it as Prime or Composite, based on the definitions provided:

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📌 Definitions Recap:

- Factors: Numbers you multiply to get another number (including 1 and the number itself).
- Prime Number: Has exactly two factors — 1 and itself.
- Composite Number: Has more than two factors.

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Now, let’s go through each number one by one:

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✔ 1. Number: 10

- Factors: 1, 2, 5, 10 → 4 factors
- More than 2 → Composite

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✔ 2. Number: 5

- Factors: 1, 5 → 2 factors
- Exactly 2 → Prime

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✔ 3. Number: 12

- Factors: 1, 2, 3, 4, 6, 12 → 6 factors
- More than 2 → Composite

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✔ 4. Number: 18

- Factors: 1, 2, 3, 6, 9, 18 → 6 factors
- More than 2 → Composite

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✔ 5. Number: 41

- Check divisibility: 41 is not divisible by 2, 3, 5, or 7 (next primes).
√41 ≈ 6.4 → only need to check up to 6.
- Factors: 1, 41 → 2 factors
- Exactly 2 → Prime

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✔ 6. Number: 15

- Factors: 1, 3, 5, 15 → 4 factors
- More than 2 → Composite

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✔ 7. Number: 2

- Factors: 1, 2 → 2 factors
- Exactly 2 → Prime *(Note: 2 is the only even prime number)*

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✔ 8. Number: 49

- 49 = 7 × 7
- Factors: 1, 7, 49 → 3 factors
- More than 2 → Composite

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✔ 9. Number: 73

- Check divisibility: Not divisible by 2, 3, 5, 7, or 11 (next primes).
√73 ≈ 8.5 → check up to 7.
- Factors: 1, 73 → 2 factors
- Exactly 2 → Prime

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✔ 10. Number: 33

- 33 = 3 × 11
- Factors: 1, 3, 11, 33 → 4 factors
- More than 2 → Composite

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✔ 11. Number: 21

- 21 = 3 × 7
- Factors: 1, 3, 7, 21 → 4 factors
- More than 2 → Composite

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## ✔ Final Completed Table:

| Number | List of Factors | Prime or Composite |
|--------|-------------------------|--------------------|
| 10 | 1, 2, 5, 10 | Composite |
| 5 | 1, 5 | Prime |
| 12 | 1, 2, 3, 4, 6, 12 | Composite |
| 18 | 1, 2, 3, 6, 9, 18 | Composite |
| 41 | 1, 41 | Prime |
| 15 | 1, 3, 5, 15 | Composite |
| 2 | 1, 2 | Prime |
| 49 | 1, 7, 49 | Composite |
| 73 | 1, 73 | Prime |
| 33 | 1, 3, 11, 33 | Composite |
| 21 | 1, 3, 7, 21 | Composite |

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## 💡 Tip for Students:
To find factors quickly:
- Start with 1 and the number itself.
- Check divisibility by 2, 3, 4, 5… up to the square root of the number.
- If you find a factor, its pair is also a factor (e.g., if 3 divides 12, then 12 ÷ 3 = 4 is also a factor).

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✔ All done! This worksheet helps reinforce understanding of prime vs. composite numbers through practice. Great job working through it!