Fingers play a crucial role in the development of numerical skills. They are already in link with non-symbolic treatment of analogic quantities because of a neuro-anatomic overlap of the areas devoted to finger perception and those responsible for the “number sense”. Then, fingers are concretely involved in early stages of learning mathematic where children progressively connect manipulated numerosities to their names. Finally, fine dexterity and finger gnosia seem to be also linked to symbolic skills, even when fingers are no longer practically used. However, we do not know exactly if fingers are involved in the numerical cognition only because of the neuro-anatomic constraint or through more functional manipulations. In order to clarify this issue, we studied performance of children with congenital motor impairments in comparison with a control group. We observed which skills were preserved or impaired, when fingers could not have played their usual role. Thus, we drew theoretical and pedagogical conclusions. Key words: fine motor skills; finger sense; mathematical cognition; cerebral palsy.