1 and 2 are factors of all even numbers.
The GCF of any two odd numbers is always odd because odd numbers don't have any even factors. The GCF of any two even numbers is always even because even numbers are divisible by two and any common factors would have at least one two in common. The GCF of an even and an odd number is odd because odd numbers don't have any even factors.
Mostly yes, but not always.
Yes because if it is even then all of it's factors will be even. It is fairly different if it's an odd number. But I will not get into that.
No. Two numbers are relatively prime if they have no prime factors in common. Two even numbers will have 2 as a prime factor in common.
At least one of the factors of an even number must be even, because the product of odd factors is always odd.
do you mean " what does all even numbers have as factors?"? then the number two.
The GCF of two even numbers is always even.
The sum of two odd numbers is always even.
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.
The sum of two even numbers is always an even number.
The sum of two even numbers is always an even number.
Two odd numbers are always even