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Psychologist and author Richard Wiseman, who brought us Ten Bets You Will Never Lose and a lot of other stuff, has a spooky trick involving a haunted doll. Can you find it? I think you can! It's simple math at work, but you can easily freak someone out with this. -via Tastefully Offensive
Click here for the explanation.
See, after the first sequence, no matter which direction you move, you will end up on either number two or number four. Then he takes away the two on the ends, so the only way you can move is to the middle. Once the bag on the left is removed, you only have one place to move. And that's exactly where he wants you.