Two dice are tossed simultaneously. What is the probability that “either the sum of top faces of dice is six

Question

or both top faces are similar”?

Answer 1

sum of six:
1,5 2,4 3,3 4,2 5,1 ---> 5 ways
top faces the same:
1,1 2,2 3,3 4,4 5,5 6,6 ---> 6 ways

number of ways of our event = 5+6-1 (can't count the 3,3 twice)
= 10

prob(of our event) = 10/36 = 5/18