DIDACTIC FOUNDATIONS OF TEACHING ARITHMETIC OPERATIONS WITH MULTI-DIGIT NUMBERS IN ELEMENTARY GRADES.

This article examines the didactic foundations of teaching arithmetic operations with multi-digit numbers to primary school students. The study aims to identify the psychological and pedagogical conditions for forming algorithmic competencies in addition, subtraction, multiplication, and division, and to develop effective methodological approaches. The theoretical framework is grounded in activity theory, principles of the positional number system, and the concept of visual-didactic tools. The results of a pedagogical experiment confirm the effectiveness of the developed methodology: the quality of students' knowledge increased by 28–34%.