Computational thinking (CT) is currently considered a fundamental ability that must be developed, from an early age, alongside reading, writing and arithmetic. The most common and most used is by using the computer, but analogue games can play a fundamental role, acting as a teaching tool for the development of six associated practices of CT: abstraction, decomposition, pattern recognition, algorithms and debugging. In this context, we present a study with students in the 1st year of the Degree in Basic Education at a university in the north of Portugal, whose objective was to analyze how the use of a card game, which works on the four basic operations and the mental calculation associated with these operations, allows the development of CT skills. This exploratory and descriptive study was carried out in two phases: In the first phase, students had the opportunity to play a card game and in the second phase they responded to a questionnaire about their opinion on the use of the game as a way for facilitating the development of computational thinking. Therefore, the data collection instrument was a questionnaire constructed by the authors. For processing the data, we opted for the content analysis of the responses given by participating students to the questionnaire. The results show that these future primary teachers consider the card games in question useful in promoting the development of computational thinking and mental calculation skills.