Jack tells Jill, "This isn't the $5 bill you left on the the table. I found it between pages 15 and 16 of Harry Potter."
Jill retorts, "You're lying and I can prove it." How did Jill know?
Harry Potter, like all other books, has odd-numbered pages on the right. Therefore, pages 15 and 16 are the front and back of a single page, and nothing could have been found between them.
10 candles stand burning in a dining room. A strong breeze blows in through an open window and extinguishes 3 of them. Assuming the wind doesn't extinguish any more candles, how many candles do you have left in the end?