When a roulette wheel is spun, the score will be a number from 0 to 36 inclusive. Each score is equally likely. Find the probability that the score is

a) an even number

b) A multiple of 3

c) a multiple of 6

d) an odd number which is not a multiple of 3

I can do a, b, and c, but for d, is there a mathematical way to do it? I took a less mathematical approach and I just wrote out all the numbers from 0 to 36 and counted which numbers were odd and not a multiple of 3.