Prime and Composite Numbers worksheet for grades 4 and 5 | Live ... - Free Printable

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:

---

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 → none divide 67.
→ 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 factors are 1 and 19. Try dividing by 2, 3, 5, 7, 11, 13, 17 — none work.
→ Prime

5) 41
Not even, not ending in 5, sum=5 → not divisible by 3.
√41 ~ 6.4 → test 2,3,5 → none divide.
→ 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
Check divisibility: not even, not ending in 5, sum=2+9+3=14 → not divisible by 3.
√293 ~ 17.1 → test primes up to 17: 7? 293÷7≈41.8 → no. 11? 293÷11≈26.6 → no. 13? 293÷13≈22.5 → no. 17? 293÷17≈17.2 → no.
→ Prime

9) 157
Not even, not ending in 5, sum=1+5+7=13 → not divisible by 3.
√157 ~ 12.5 → test 7, 11 → 157÷7≈22.4, 157÷11≈14.2 → no.
→ Prime

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

11) 91
This is tricky! 91 = 7 × 13 → so it’s composite.
→ Composite

12) 37
Not even, not ending in 5, sum=10 → not divisible by 3.
√37 ~ 6.1 → test 2,3,5 → none divide.
→ Prime

13) 383
Not even, not ending in 5, sum=3+8+3=14 → not divisible by 3.
√383 ~ 19.5 → test primes up to 19:
7? 383÷7≈54.7 → no
11? 383÷11≈34.8 → no
13? 383÷13≈29.4 → no
17? 383÷17≈22.5 → no
19? 383÷19≈20.1 → no
→ Prime

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

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

16) 31
Not even, not ending in 5, sum=4 → not divisible by 3.
√31 ~ 5.5 → test 2,3,5 → none divide.
→ Prime

17) 79
Not even, not ending in 5, sum=16 → not divisible by 3.
√79 ~ 8.9 → test 2,3,5,7 → 79÷7≈11.2 → no.
→ Prime

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

---

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