Challenge #1

Question:

Kimberly has an integer between -16 and 16 (inclusive) in her mind. You can ask her some questions, each of which must be in the form of "is your number strictly less than x?" (x can be any real number). You can decide the question you are going to ask according to the answers of previous questions. In the worst case, at least how many questions should be asked to know the exact value of the integer Kimberly has in mind?