"A multiple choice test consists of four questions, each with four possible answers, only one of which is correct. You randomly guess each answer. What is the probability of:

A: Getting them all right

B: Getting at least one right"

A is (1/4)^4, which is 1/16. B is (1/4)^1, which is 1/4. I don't know what "proper" notation for this is, though.