A.
Factors of 36: 1, 2, 3, 4, 6, 9, 12, 18, and 36
Factors of 48: 1, 2, 3, 4, 6, 8, 12, 16, 24, and 48.
Common Factors: 1, 2, 3, 4, 6, and 12
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B.
Factors of 16: 1, 2, 4, 8, and 16.
Factors of 56: 1, 2, 4, 7, 8, 14, 28, and 56
Common Factors: 1, 2, 4, and 8
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C.
Factors of 30: 1, 2, 3, 5, 6, 10, 15 and 30.
Factors of 75: 1 , 3 , 5 , 15 , 25 and 75
Common Factors: 1, 3, 5, and 15.
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D.
Factors of 54: 1, 2, 3, 6, 9, 18, 27, 54
Factors of 90: 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45, 90.
Common Factors: 1, 2, 3, 6, 9, and 18.
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E.
Whenever finding the greatest common factors of any pair of numbers it is necessary to list all the factors of each number. Then find the number that appears in both!