A Number Talk is a brief activity (10-15 minutes in length) that is designed to support students' mathematical sense making and promote flexible thinking. During a Number Talk, students engage in mental computations. Number Talks help students do the following: (1) Develop number sense focused on making sense of quantity and mathematical relationships; (2) Understand that there can be many ways to solve a mathematics problem; and (3) Learn to trust their own reasoning, which helps build intellectual autonomy (Humphreys and Parker 2015). This article discusses the nuts and bolts of engaging students in Number Talks, the benefits of Number Talks for high school students, how to get started with Number Talks, and getting the most out of Number Talks. A bibliography is included.