What is the probability that the outcome of the roll is an even sum or a sum that is a multiple of 3?

All EVEN sums =
2=1/36
4 =3/36
6=5/36
8=5/36
10=3/36
12=1/36
Add up all the probabilities and you get: 18/36 = 1/2
All multiples of 3=
3=2/36
6=5/36
9=4/36
12=1/36
Add up all the probabilities and you get =12/36 = 1/3