The greatest common factor (GCF) is often also called the greatest common divisor (GCD) or highest common factor (HCF). Keep in mind that these different terms all refer to the same thing: the largest integer which evenly divides two or more numbers.
The greatest common factor of 17 and 18 is 1
The GCF of consecutive integers is 1.
The GCF is 1.
Since 17 is a prime number, the greatest common factor of 17, 18, and 20 is 1.
18
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 1.
18 is the greatest factor of 18.
The GCF is 1.
Since 18 is a factor of 90 and it is the largest factor of itself, the greatest common factor of 18 and 90 is 18.Since 18 is a factor of 90, it is automatically the GCF.
The greatest common factor is 18.
The greatest common factor of 18 and 55 is 1.
The greatest common factor of 39 and 18 is definitely 3.