<p>This paper presents <i>NumbersPlayRoom VR</i>, an exploratory study on a virtual reality serious game designed to support the learning of fundamental numerical skills in primary school children, particularly those with numerical learning difficulties such as Developmental Dyscalculia. Grounded in numerical cognition and multimedia learning theories, the system contains three mini-games that target complementary components of mathematical reasoning: arithmetic fluency (<i>Mental Calculation</i>), procedural column-based calculation (<i>Column Counting</i>), and magnitude representation and mental number line (<i>Block Sorting</i>). The experience places the learner in a virtual classroom where they can interact with numerical content through embodied actions in an immersive, distraction-free environment. We report a two-phase empirical evaluation. In the first phase, adult users tested the application and provided usability and appreciation feedback, indicating high perceived usability and positive responses to the game design. In the second phase, the system was deployed in a primary school with children, including students with certified learning disorders. Quantitative data from an emoji-based survey and in-game performance metrics were combined with qualitative observations from teachers and supervisors. Overall, the results suggest that <i>NumbersPlayRoom VR</i> is usable and engaging and that it provides preliminary evidence of its potential as a complementary tool to support numerical cognition in primary school children.</p>