A good-quality teacher may determines a good-quality learning, thus good-quality students will be the results. In order to have a good-quality learning, a lot of strategies and methods can be adopted. The objective of this research is to improve students' ability in determining the rules of a numeric sequence and analysing the effectiveness of the implementation of "the n-term" to determine the rule of a number. A research classroom method administered at the State Islamic Junior High School Malang-Indonesia is adopted. The results show that the implementation of "the n term" formula may improve the students' ability in determining the numeric sequence in the State Islamic Junior High School Malang-Indonesia. Some suggestions are offered: a) observation of learning activities should always be made to obtain inputs on the implementation; b) learning innovations should always be made to base on facts obtained through observation; c) the results of this study may be used for reference for further development in learning numeric sequences that enable students to be more interested in studying mathematics.