The greatest common factor of 42 and 66 is 6.6
The GCF of 24, 42, and 66 is 6.
6
The GCF is 6.
The GCF is 6.
The GCF is 6.
The GCF is 6.
The GCf is 6.
The GCF is 6.
The GCF is 6.
If you mean the greatest common divisor (or factor), the answer is 6
The GCF is 6.