Terry T. Y. Wong, Eason Sai-Kit Yip
The knowledge of various types of numbers, such as integers and fractions, has been shown to be crucial for students’ success in mathematics. However, the significance of negative number knowledge has not been explored enough. This study aims to investigate the role of negative number knowledge in mathematics achievement. A group of seventh graders (n = 192) in Hong Kong were assessed on their understanding of positive and negative integers, mathematics achievement, fluid intelligence, working memory, and inhibition. Using hierarchical linear models, the study found that negative number understanding significantly predicted mathematics achievement, even after controlling for school, general cognitive skills, and positive number understanding. The findings confirm the importance of negative number understanding in early adolescents’ mathematics learning. Educators should pay more attention to this aspect of numerical magnitude. (PsycInfo Database Record (c) 2025 APA, all rights reserved)