The conceptual representation of numbers is dealt with in Chapter 12. However, it is interesting to note at this juncture that there is a double dissociation between spared numbers and impairments of other concepts (Cappelletti et al., 2002), and impaired numbers but spared knowledge of other concepts (Cipolotti et al., 1991). It is often argued that the representation of number knowledge is a true categorical distinction (Dehaene et al., 2003).