Computational estimation is an important skill necessary for students' mathematical development. Students who can estimate well for computations rely on an understanding of many mathematical topics, including a strong number sense, which facilitates understanding the mathematical operations and contextual evidence within a problem. In turn, good estimation skills improve students' ability to do exact computations and help them determine the reasonableness of their solutions. There exists research regarding estimation, its significance, and some of the possible estimation strategies (National Council of Teachers of Mathematics, 2000; Sowder & Wheeler, 1989; Van de Walle, Karp, & Bay-Williams, 2010). While this research exists, it does not adequately address the particular ways students understand and perform estimations. In this study, we asked middle school students to answer both written and oral problems, which suggested the use of estimation. Our findings contribute to a more comprehensive definition of computational estimation and its strategies by presenting student examples. These student examples serve as a model for identifying the significance of computational estimation and its link to other conceptual mathematical knowledge.