In this study, we report a work of using one-to-one technologies to motivate a class of elementary students in extensive practice of mental calculation. Specifically, each student in the classroom uses a notebook computer to practice mental calculation. The goal of extensive practice is to increase procedural fluency in mental calculation. Generally, except for a small portion of highly motivated students, the rest of students easily get bored in extensive practice and soon become reluctant to practice more. To motivate the students to practice mental calculation more, some gaming elements were implanted to promote student engagement in extensive practice. As a result, all the students practiced a lot and encouraging improvements of student learning achievement were reported by the classroom teacher. Among others, their achievement scores of a subsequent summative evaluation were dramatically improved in comparison with other classes in the same school.