Let’s solve each problem step by step. We’re looking for the
Highest Common Factor (HCF) — also called GCD — which is the biggest number that divides both numbers evenly.
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1. 16 and 22
Factors of 16: 1, 2, 4, 8, 16
Factors of 22: 1, 2, 11, 22
Common factors: 1, 2 → Highest =
2
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2. 11 and 22
Factors of 11: 1, 11
Factors of 22: 1, 2, 11, 22
Common factors: 1, 11 → Highest =
11
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3. 7 and 21
Factors of 7: 1, 7
Factors of 21: 1, 3, 7, 21
Common factors: 1, 7 → Highest =
7
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4. 4 and 14
Factors of 4: 1, 2, 4
Factors of 14: 1, 2, 7, 14
Common factors: 1, 2 → Highest =
2
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5. 10 and 40
Factors of 10: 1, 2, 5, 10
Factors of 40: 1, 2, 4, 5, 8, 10, 20, 40
Common factors: 1, 2, 5, 10 → Highest =
10
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6. 5 and 50
Factors of 5: 1, 5
Factors of 50: 1, 2, 5, 10, 25, 50
Common factors: 1, 5 → Highest =
5
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7. 7 and 49
Factors of 7: 1, 7
Factors of 49: 1, 7, 49
Common factors: 1, 7 → Highest =
7
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8. 3 and 24
Factors of 3: 1, 3
Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24
Common factors: 1, 3 → Highest =
3
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9. 22 and 44
Factors of 22: 1, 2, 11, 22
Factors of 44: 1, 2, 4, 11, 22, 44
Common factors: 1, 2, 11, 22 → Highest =
22
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10. 42 and 21
Factors of 42: 1, 2, 3, 6, 7, 14, 21, 42
Factors of 21: 1, 3, 7, 21
Common factors: 1, 3, 7, 21 → Highest =
21
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Final Answer:
1. 2
2. 11
3. 7
4. 2
5. 10
6. 5
7. 7
8. 3
9. 22
10. 21
Parent Tip: Review the logic above to help your child master the concept of greatest common factors fractions worksheet.
