To do this, you first need to split the numbers into their prime factors:
33 = 3x11
38 = 2x19
The next step would be to find any common prime factors. In this case, however, there are none. Therefore the GCF of 33 and 38 is 1.
The GCF is 33.
66
The GCF of 38 and 76 is 38. Since 38 is a factor of 76, it is automatically the GCF.
The GCF of 33 and 66 = 33
The GCF is 2.
The GCF is 2.
The GCF is 2.
The GCF is 2.
The GCF is 22.
The GCF is 2.
The GCF is 2.
The GCF is 2.