Factors of 12: (1), (2), 3, (4), 6, and 12.
Factors of 16: (1), (2), (4), 8, and 16.
Common factors of 12 and 16 are: 1, 2 and 4.
(b) 8 and 12
Solution:
Factors of 8: (1), (2), (4), and 8.
Factors of 12: (T), (2), 3, (4), and 12.
Common factors of 8 and 12 are: 1, 2, and 4
(c) 4 and 16
Solution:
Factors of 4: (1), (2), and (4).
Factors of 16: (1), (2), (4), 8, and 16. Common factors of 4 and 16 are: 1, 2 and 4
(d) 2 and 9
Solution:
Factors of 2: (1), and 2 Factors of 9: (1), 3 and 9
Common factor of 2 and 9 is only 1.
(e) 3 and 5
Solution:
Factors of 3: (1) and 3.
Factors of 5: (1) and 5.
Common factor of 3 and 5 is only 1.
(f ) 12 and 15
Solution:
Factors of 12: (1), (2), 3, 4, 6 and 12.
Factors of 15: (1), (3), 5 and 15.
Common factors of 12 and 15 are: 1 and 3.
(f) 20 and 5
Solution:
Factors of 20: (1) 2, 4, (5) 10 and 20.
Factors of 5: (1) and (5).
Common factors of 20 and 5 are: 1 and 5.
(g) 9 and 21
Solution:
Factors of 9: (1), (3) and 9.
Factors of 21: (1), (3), 7 and 21.
Common factors of 9 and 21 are: 1 and 3.
(h) 6 and 27
Solution:
Factors of 6: (1), 2, (3) and 6.
Factors of 27: (1), (3), 9 and 27.
Common factors of 6 and 27 are: 1 and 3.
What do you notice about the common factors of different pairs of numbers? Discuss in class.
Solution:
Do it yourself.