What precursor abilities form the building blocks of numerical representations? Two abilities were investigated: the ability to mentally represent small numerosities, indexed by subitizing speed (Butterworth, 1999), and the ability to mentally represent ones fingers, indexed by finger gnosis (Butterworth, 1999; Penner-Wilger & Anderson, 2008). We examined the longitudinal relation between these abilities in Grade 1 and tasks assessing numerical representation in Grade 2symbolic number comparison and number-line estimation for 100 Canadian children. Finger gnosis (but not subitizing speed) in Grade 1 was related to childrens symbolic distance effect in number comparison and to the linearity of childrens estimates in Grade 2. Thus, children with better finger gnosis scores had lower symbolic distance effects and more accurate estimates, reflecting a more precise mapping between numerals and their associated magnitude.