Numbers, visible or not, are often at the core of game design. They are the expression of the designer's vision of "how the world works." There are considerations that go beyond simply balancing an equation, however. Through the selection of numbers such as scores, abilities, damage ranges, and even prices, we are often crafting what a player perceives, believes, and even feels. Through extensive use of (often amusing) examples, this lecture will demonstrate what our numbers may be conveying and explore ways that we can leverage the psychology of numbers to build more engaging games.