All even numbers have two as a factor. Any two even numbers have (at the least) two as a common factor. That means the GCF of any two even numbers will have two as a factor. Any number that has two as a factor is even.
The GCF of any set of odd numbers is odd because odd numbers don't have any even factors.
Any consecutive even numbers have a GCF of 2.
The GCF of any two odd numbers is also odd.
This can't be determined. The GCF of 3 and 5 is 1. The GCF of 11 and 33 is 11. There's no rule that covers any and all odd numbers.
The GCF is 1.
The GCF of any two odd numbers is always odd. The GCF of any two even numbers is always even. The GCF of an odd and an even number is always odd.
Any consecutive even numbers.
The GCF of 18, 20, and 26 is 2. The GCF of a set of numbers can't be any larger than the smallest difference between the numbers. The smallest difference within this set of numbers is 2. Since all of the numbers in the set are even, 2 is the greatest common factor.
The GCF of all the composite numbers under 100 is 1. For e.g 4 & 9 are composite numbers & their GCF is 1, so if we take other composite numbers along with 4 & 9 the GCF will be 1.
When answering a question such as "Name two numbers whose GCF is 6" there are two quick and easy ways to do this. One is to name 6 and any multiple of 6. The other is to name any multiples of 6 that differ by 6.
Prime and relatively prime numbers all have a GCF of 1.