You need at least two numbers to find a GCF.
A single number cannot have a greatest common factor - a greatest common factor (GCF) is used to compare two or more numbers.
3
The GCF is 3.
The GCF is 3.
The GCF is 3.
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 17.
The GCF for 29 51 is 1.
The GCF of 42 and 51 is 3.
255 = 51 x 5 so 51 is GCF
The GCF of 39 and 51 is 3.3
The GCF is 1.