Just 3.
1 and 3
The common factors are: 1, 2
All the common factors of 42 and 231 are: 1, 3, 7, 21.
1 and 3
The prime factors of 28 are 2,2 and 7 The prime factors of 42 are 2,3 and 7 Thus the common factors are 1,2,7 and 14.
1, 2, 7 and 14 are the common factors of 28 and 42. Since all of the numbers are common factors, we will not be able to select two.
The factors of 14 are 1, 2, 7, and 14 The factors of 42 are 1, 2, 3, 7, 14, 21, and 42 The Common factors of 14 and 42 are 1, 2, 7, and 14
The common factors are: 1, 2, 7, 14.
The common factors are: 1, 2
Factors of 28... 1,2,4,7,14,28 Factors of 42... 1,2,3,6,7,14,21,42 GCF = 14
The factors of 42 are 1, 2, 3, 6, 7, 14, 21, 42 For them to be common, they need to be compared to another set of factors.