Math worksheet for finding the greatest common factor of number pairs, including a playful cartoon face.

To find the Greatest Common Factor (GCF) for each pair, we need to list the factors of both numbers and find the largest one they share.

Here is the step-by-step breakdown for each problem:

1. 15 and 12
* Factors of 15: 1, 3, 5, 15
* Factors of 12: 1, 2, 3, 4, 6, 12
* The largest number in both lists is 3.

2. 8 and 10
* Factors of 8: 1, 2, 4, 8
* Factors of 10: 1, 2, 5, 10
* The largest number in both lists is 2.

3. 14 and 21
* Factors of 14: 1, 2, 7, 14
* Factors of 21: 1, 3, 7, 21
* The largest number in both lists is 7.

4. 16 and 20
* Factors of 16: 1, 2, 4, 8, 16
* Factors of 20: 1, 2, 4, 5, 10, 20
* The largest number in both lists is 4.

5. 25 and 30
* Factors of 25: 1, 5, 25
* Factors of 30: 1, 2, 3, 5, 6, 10, 15, 30
* The largest number in both lists is 5.

6. 24 and 50
* Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24
* Factors of 50: 1, 2, 5, 10, 25, 50
* The largest number in both lists is 2.

7. 22 and 20
* Factors of 22: 1, 2, 11, 22
* Factors of 20: 1, 2, 4, 5, 10, 20
* The largest number in both lists is 2.

8. 15 and 35
* Factors of 15: 1, 3, 5, 15
* Factors of 35: 1, 5, 7, 35
* The largest number in both lists is 5.

9. 8 and 26
* Factors of 8: 1, 2, 4, 8
* Factors of 26: 1, 2, 13, 26
* The largest number in both lists is 2.

10. 6 and 27
* Factors of 6: 1, 2, 3, 6
* Factors of 27: 1, 3, 9, 27
* The largest number in both lists is 3.

11. 21 and 63
* Factors of 21: 1, 3, 7, 21
* Factors of 63: 1, 3, 7, 9, 21, 63
* Since 21 goes into 63 exactly (21 x 3 = 63), the GCF is 21.

12. 16 and 54
* Factors of 16: 1, 2, 4, 8, 16
* Factors of 54: 1, 2, 3, 6, 9, 18, 27, 54
* The largest number in both lists is 2.

13. 18 and 81
* Factors of 18: 1, 2, 3, 6, 9, 18
* Factors of 81: 1, 3, 9, 27, 81
* The largest number in both lists is 9.

14. 42 and 70
* Factors of 42: 1, 2, 3, 6, 7, 14, 21, 42
* Factors of 70: 1, 2, 5, 7, 10, 14, 35, 70
* The largest number in both lists is 14.

15. 27 and 36
* Factors of 27: 1, 3, 9, 27
* Factors of 36: 1, 2, 3, 4, 6, 9, 12, 18, 36
* The largest number in both lists is 9.

16. 16 and 40
* Factors of 16: 1, 2, 4, 8, 16
* Factors of 40: 1, 2, 4, 5, 8, 10, 20, 40
* The largest number in both lists is 8.

17. 24 and 60
* Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24
* Factors of 60: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60
* The largest number in both lists is 12.

Final Answer:
15 and 12: 3
8 and 10: 2
14 and 21: 7
16 and 20: 4
25 and 30: 5
24 and 50: 2
22 and 20: 2
15 and 35: 5
8 and 26: 2
6 and 27: 3
21 and 63: 21
16 and 54: 2
18 and 81: 9
42 and 70: 14
27 and 36: 9
16 and 40: 8
24 and 60: 12