Coin-operated karaoke machines are exploding in popularity. Seoul, South Korea -- A dollar can buy a pack of gum, a can of soda or a bag of chips. And in South Korea, it can buy an opportunity to sing ...

Slot machines are one of the most popular games in casinos, attracting players with bright lights, exciting sounds, and the thrill of hitting a jackpot. But have you ever wondered how they really work ...