1,2,4 and 8.
8
The common factors of 56 and 18 are 1 and 2.
The common factors of 38 and 56 are 1 and 2.
The common factors of 54 and 144 are: 1, 2, 3, 6, 9, and 18
The common factors of 90 and 144 are: 1, 2, 3, 6, 9, and 18
Since 28 is a factor of 56, all of the factors of 28 are common to 56.
The common factors of 52 and 56 are: 1, 2, and 4
The common factors of 63 and 56 are: 1, 7
The common factors of 12 and 56 are: 1, 2, and 4
Since 4 is a factor of 56, all of its factors are common.
Common factors of 45 and 144 are: 1, 3, and 9.
The common factors of 34 and 56 are 1 and 2