The GCF is 1.
GCF(240, 405) = 15 And there can be only one GCF. The word "greatest" is a bit of a giveaway. It is a superlative ad that means there can only be one.
The GCF is 1.
The greatest common factor of 15 and 2 is one.
When the smaller one is a factor of the larger one. (That also means the larger one is a multiple of the smaller one.) The smaller number is the GCF of both.
The GCF of one number is itself. To find the GCF, more than one number is needed.
One number can't have a GCF!
The GCF of one number is itself.
The GCF of one number is itself.
The GCF of one number is itself.
The GCF of one number is itself.
The GCF of one number is itself.
The GCF of one number is itself.
The GCF of one number is itself.
The GCF of one number is itself.
The GCF of one number is itself.
The GCF of one number is itself.