The present work aims to contribute to the development of processes associated with numerical thinking in the context of addition and multiplication, in third grade students, from the use of the CPA method and the problem solving approach as a didactic strategy. This strategy is framed in the qualitative paradigm and is descriptive in nature, as it aims to expose progress and difficulties of the students regarding the approach and solution of additive and multiplicative problems. During the intervention process, three types of instruments are applied: diagnostic test, intervention guide (concrete phase), and completion test (pictorial and abstract phase). Among the results obtained, the advances regarding the ability to tackle and solve additive and multiplicative problems are highlighted, evidencing the use of the various structures (change, combination, comparison and equalization) in the case of the additive and in the context multiplicative (multiplying factor, repeated addition, ratio, Cartesian product), where the use of the specific phase was decisive. In addition, progress was evidenced in the reasoning processes, communication of ideas, modeling, procedural exercise, and of course in problem solving.