If you add an even number and an odd number, the result is
Note
An even number is 2k and an odd is 2m+1; their sum is 2(k+m)+1, which is odd.
If you add an even number and an odd number, the result is
An even number is 2k and an odd is 2m+1; their sum is 2(k+m)+1, which is odd.