Prime and Composite Numbers worksheet for students to classify numbers as prime or composite.

Let’s go through each number one by one and decide if it’s prime or composite.

Remember:
- A prime number has exactly two factors: 1 and itself.
- A composite number has more than two factors (it can be divided evenly by numbers other than 1 and itself).

We’ll check each number:

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1) 67
Check divisibility: Not even, doesn’t end in 5, sum of digits = 6+7=13 (not divisible by 3). Try dividing by primes up to √67 ≈ 8.2 → try 2, 3, 5, 7.
67 ÷ 7 ≈ 9.57 → not whole.
→ Prime

2) 530
Ends in 0 → divisible by 2 and 5 → definitely composite.
→ Composite

3) 825
Ends in 5 → divisible by 5 → composite.
→ Composite

4) 19
Only divisible by 1 and 19. Check primes up to √19 ≈ 4.3 → try 2, 3.
19 ÷ 2 = 9.5, 19 ÷ 3 ≈ 6.33 → no.
→ Prime

5) 41
√41 ≈ 6.4 → check 2, 3, 5.
Not even, 4+1=5 (not div by 3), doesn’t end in 5.
→ Prime

6) 87
Sum of digits: 8+7=15 → divisible by 3 → 87 ÷ 3 = 29 → composite.
→ Composite

7) 62
Even number → divisible by 2 → composite.
→ Composite

8) 293
√293 ≈ 17.1 → check primes up to 17: 2, 3, 5, 7, 11, 13, 17.
Not even, 2+9+3=14 (not div by 3), doesn’t end in 5.
293 ÷ 7 ≈ 41.85 → no
293 ÷ 11 ≈ 26.6 → no
293 ÷ 13 ≈ 22.5 → no
293 ÷ 17 ≈ 17.2 → no
→ Prime

9) 157
√157 ≈ 12.5 → check 2, 3, 5, 7, 11.
Odd, 1+5+7=13 (not div by 3), not ending in 5.
157 ÷ 7 ≈ 22.4 → no
157 ÷ 11 ≈ 14.27 → no
→ Prime

10) 69
6+9=15 → divisible by 3 → 69 ÷ 3 = 23 → composite.
→ Composite

11) 91
Try dividing: 91 ÷ 7 = 13 → yes! So 7 × 13 = 91 → composite.
→ Composite

12) 37
√37 ≈ 6.1 → check 2, 3, 5.
Odd, 3+7=10 (not div by 3), not ending in 5.
→ Prime

13) 383
√383 ≈ 19.5 → check primes up to 19: 2, 3, 5, 7, 11, 13, 17, 19.
Odd, 3+8+3=14 (not div by 3), not ending in 5.
383 ÷ 7 ≈ 54.7 → no
383 ÷ 11 ≈ 34.8 → no
383 ÷ 13 ≈ 29.46 → no
383 ÷ 17 ≈ 22.5 → no
383 ÷ 19 ≈ 20.15 → no
→ Prime

14) 445
Ends in 5 → divisible by 5 → composite.
→ Composite

15) 16
Even, also 4×4 → clearly composite.
→ Composite

16) 31
√31 ≈ 5.5 → check 2, 3, 5.
Odd, 3+1=4 (not div by 3), not ending in 5.
→ Prime

17) 79
√79 ≈ 8.9 → check 2, 3, 5, 7.
Odd, 7+9=16 (not div by 3), not ending in 5.
79 ÷ 7 ≈ 11.28 → no
→ Prime

18) 926
Even → divisible by 2 → composite.
→ Composite

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Final Answer:
1) Prime
2) Composite
3) Composite
4) Prime
5) Prime
6) Composite
7) Composite
8) Prime
9) Prime
10) Composite
11) Composite
12) Prime
13) Prime
14) Composite
15) Composite
16) Prime
17) Prime
18) Composite