This is a great way to motivate kids to work with spelling or vocabulary words! I figure out which of my spelling or vocabulary words are "dollar words" (words that have a "value" of exactly one dollar), and let my students try to work out the math. If one of them is able to do it, they all get fired up and want to try! It's a great pre-class activity to get students focused. It can also be used in a math center. Best of all, it's FREE!