The answer may not be the focal point of asking these questions. The interviewer would like to how you approach an unfamiliar, out-of-the-box problem.
There is no right answer to a creative thinking question. The interviewer may be looking for a variety of things from you by asking this type of question. For example, how quickly can you create a range of solutions reveals your thoughtfulness and quick-thinking ability. A key factor to keep in mind is the interviewer is wanting to see if you can articulate your creative solution with some reasoning.