Let’s go step by step to find the
proper factors of each number.
First, what is a
proper factor?
> A proper factor of a number is any factor of that number
except the number itself.
> For example, the factors of 6 are: 1, 2, 3, and 6.
> So the *proper* factors of 6 are: 1, 2, and 3 (we leave out 6).
We’ll do this for every number on the list.
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Let’s start with 15:
Factors of 15: 1, 3, 5, 15 → Proper factors:
1, 3, 5
20:
Factors: 1, 2, 4, 5, 10, 20 → Proper factors:
1, 2, 4, 5, 10
24:
Factors: 1, 2, 3, 4, 6, 8, 12, 24 → Proper factors:
1, 2, 3, 4, 6, 8, 12
16:
Factors: 1, 2, 4, 8, 16 → Proper factors:
1, 2, 4, 8
30:
Factors: 1, 2, 3, 5, 6, 10, 15, 30 → Proper factors:
1, 2, 3, 5, 6, 10, 15
18:
Factors: 1, 2, 3, 6, 9, 18 → Proper factors:
1, 2, 3, 6, 9
25:
Factors: 1, 5, 25 → Proper factors:
1, 5
21:
Factors: 1, 3, 7, 21 → Proper factors:
1, 3, 7
42:
Factors: 1, 2, 3, 6, 7, 14, 21, 42 → Proper factors:
1, 2, 3, 6, 7, 14, 21
40:
Factors: 1, 2, 4, 5, 8, 10, 20, 40 → Proper factors:
1, 2, 4, 5, 8, 10, 20
38:
Factors: 1, 2, 19, 38 → Proper factors:
1, 2, 19
60:
Factors: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60 → Proper factors:
1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30
52:
Factors: 1, 2, 4, 13, 26, 52 → Proper factors:
1, 2, 4, 13, 26
36:
Factors: 1, 2, 3, 4, 6, 9, 12, 18, 36 → Proper factors:
1, 2, 3, 4, 6, 9, 12, 18
64:
Factors: 1, 2, 4, 8, 16, 32, 64 → Proper factors:
1, 2, 4, 8, 16, 32
23:
This is a prime number! Factors: 1, 23 → Proper factors:
1
19:
Also prime! Factors: 1, 19 → Proper factors:
1
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✔ All calculations checked. Now here’s the final answer in order as shown on the worksheet:
Final Answer:
15: 1, 3, 5
20: 1, 2, 4, 5, 10
24: 1, 2, 3, 4, 6, 8, 12
16: 1, 2, 4, 8
30: 1, 2, 3, 5, 6, 10, 15
18: 1, 2, 3, 6, 9
25: 1, 5
21: 1, 3, 7
42: 1, 2, 3, 6, 7, 14, 21
40: 1, 2, 4, 5, 8, 10, 20
38: 1, 2, 19
60: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30
52: 1, 2, 4, 13, 26
36: 1, 2, 3, 4, 6, 9, 12, 18
64: 1, 2, 4, 8, 16, 32
23: 1
19: 1
Parent Tip: Review the logic above to help your child master the concept of factor worksheet grade 4.
