A single number cannot have a greatest common factor because "common" refers to factors that two or more numbers have in common. You have only one number.
The GCF is 6.
The GCF is 9.
The GCF is 4.
The GCF is 30.
50
The GCF is: 1
The GCF is 27.
The GCF is 1.
The GCF is 2.
The GCF is 3.
The GCF is 5.