Primary education students with autism spectrum disorder may present difficulties when solving arithmetical problems. Therefore, this exploratory and descriptive single case study aims to verify the suitability of a methodology based on modified conceptual models so that a student with autism spectrum disorder understands and correctly solves direct (multiplication) and inverse (division) Cartesian product problems. The study was carried out within an inclusive educational environment and consisted of baseline, training, follow-up, generalization and maintenance. The results show a functional relationship between independent and dependent variables, the student learned to solve this type of problems, generalized his learning by successfully solving two-step problems (an addition and a multiplication) and maintained what he had learned 5 weeks after the last training session. The student employed pictorial representations, the odometer strategy and counting strategies to solve the problems raised in the follow-up, generalization and maintenance sessions. Limitations and future lines of work are also discussed.