You have 11 chocolate chip cookies left, 18 macadamia nut left, and 27 oatmeal raisin cookies left. Your brother steals some. What is the smallest number of cookies your brother must take in order to be 100% certain he gets an oatmeal raisin cookie?

Question

This problem has been confusing me for ages if someone could give me an answer and how they got the answer that would be a great help!

Answer 1

11+18 = 29 that are not oatmeal
so 30 cookies will guarantee an oatmeal