The GCF is 1.
42 is the greatest factor of 42.
The GCF of 1218 and 42 is 42. The GCF of 12, 18 and 42 is 6.
The GCF is 21.
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 41.
The GCF of 18 and 42 is 6. The GCF of 42 and 56 is 14.
GCF(82, 41) = 41.