Prime and Composite Numbers worksheet for identifying factors and classifying numbers.

I'll solve this worksheet on prime and composite numbers step by step.

First, let me understand what I need to do:
1. For each number (43, 45, 47, 53, 55), I need to write its factors
2. Then determine if each number is prime or composite
3. Finally, circle all the prime numbers from the grid at the bottom

Let me start with the first part - finding factors and determining if each number is prime or composite.

For number 43:
- Factors of 43: 1, 43
- Since 43 has only two factors (1 and itself), it is a prime number.

For number 45:
- Factors of 45: 1, 3, 5, 9, 15, 45
- Since 45 has more than two factors, it is a composite number.

For number 47:
- Factors of 47: 1, 47
- Since 47 has only two factors (1 and itself), it is a prime number.

For number 53:
- Factors of 53: 1, 53
- Since 53 has only two factors (1 and itself), it is a prime number.

For number 55:
- Factors of 55: 1, 5, 11, 55
- Since 55 has more than two factors, it is a composite number.

Now for the second part - circling all the prime numbers from the grid:
The grid contains: 23, 31, 76, 55, 77, 25, 56, 47, 23, 80, 71, 37, 73, 51, 12, 89, 95

Let me identify which of these are prime numbers:
- 23: Prime (factors: 1, 23)
- 31: Prime (factors: 1, 31)
- 76: Composite (factors: 1, 2, 4, 19, 38, 76)
- 55: Composite (factors: 1, 5, 11, 55)
- 77: Composite (factors: 1, 7, 11, 77)
- 25: Composite (factors: 1, 5, 25)
- 56: Composite (factors: 1, 2, 4, 7, 8, 14, 28, 56)
- 47: Prime (factors: 1, 47)
- 23: Prime (already identified)
- 80: Composite (factors: 1, 2, 4, 5, 8, 10, 16, 20, 40, 80)
- 71: Prime (factors: 1, 71)
- 37: Prime (factors: 1, 37)
- 73: Prime (factors: 1, 73)
- 51: Composite (factors: 1, 3, 17, 51)
- 12: Composite (factors: 1, 2, 3, 4, 6, 12)
- 89: Prime (factors: 1, 89)
- 95: Composite (factors: 1, 5, 19, 95)

So the prime numbers to circle are: 23, 31, 47, 71, 37, 73, 89

Here's my complete solution:

Part 1:
1) 43 - Factors: 1, 43 - Prime
2) 45 - Factors: 1, 3, 5, 9, 15, 45 - Composite
3) 47 - Factors: 1, 47 - Prime
4) 53 - Factors: 1, 53 - Prime
5) 55 - Factors: 1, 5, 11, 55 - Composite

Part 2:
Circle these prime numbers: 23, 31, 47, 71, 37, 73, 89