You need at least two numbers to find a GCF, but I'll save you the trouble. The GCF of 1 and any other number is 1.
There cannot be a greatest common factor (GCF) of just one number. To be common there need to be at least two numbers. If you find all the factors of two or more numbers, and you find some factors are the same ("common"), then the largest of those common factors is the Greatest Common Factor.
The greatest common factor of 18 and 55 is 1.
The greatest common factor of 52 and 81 is 1
The greatest common factor of 31 and 46 is 1.
The Greatest Common Factor of 3, 11 is 1.
The greatest common factor of 1-x3 is 1, dummy.
The Greatest Common Factor (GCF) of 1 and 12 is 1
The Greatest Common Factor of 3, 8, 12: 1
The Greatest Common Factor (GCF) is: 1
21
The GCF is 1.
1 is the greatest common factor.
The greatest common factor is 1