On cloud nine. A pretty penny. The sixty-four-thousand-dollar question. Have you heard these crazy expressions? People use them even when the sky is cloud-free and there are no pennies in sight! That's because these sayings are idioms--phrases that mean something different than what the words in them actually say. But don't let idioms put you at sixes and sevens. Let's explore a variety of idioms related to money and numbers and figure out what people really mean when they use them.