EDP Tape Librarian Interview Question:
If you have seven white socks and nine black socks in a drawer, how many socks do you have to pull out blindly in order to ensure that you have a matching pair?
Answer:
if the first one is one color (say, white), and the second one is the other color (black), then the third one, no matter what the color, will make a matching pair. (Sometimes you're not supposed to think that hard.)