This bulletin is written to expand upon and illustrate the place of arithmetic in a modern program of the kind described in Bulletin 1949, No. 12, "The Place of Subjects in the Curriculum." This bulletin, "How Children Use Arithmetic," shows how children develop arithmetic abilities. It discusses teaching methods that grow out of recent research. It is a digest of ideas and practices reported by teachers and observed in classrooms here and there. It does not dwell on fine points of instructions and analysis of numbers. These are discussed at length in good professional books on arithmetic teaching. It does attempt to give an overview of some of the problems in teaching with which the modern teacher deals as she helps her pupils to understand and use number concepts effectively. It illustrates ways in which boys and girls are helped to enrich each day's experiences through arithmetic and to make the subject consciously a part of life. This bulletin contains the following: (1) Foreword; (2) How much arithmetic today?; (3) What arithmetic is taught?; and (4) How is arithmetic taught? (Contains 8 footnotes.) [Best copy available has been provided.]