The capacity to perceive and reason about numbers is a foundational capacity in not only human adults, but also infants and many species of animals.  Infants and animals possess a numerical system which can calculate the exact number of a small set of objects as well as the approximate number (i.e., magnitude) of a large set of objects.  These nonverbal populations can calculate magnitudes regardless of whether they are presented visually or auditorally, and there is evidence for an abstract numerical “code” which transcends the specific modality of presentation.  Infants and animals have the ability to mathematically manipulate these represented numbers, performing operations which are analogous to addition, subtraction, division, and ordering.  The cognitive structure to perform such operations is functional at a very early stage in development, although it becomes more precise as the brain matures and, in the case of children, language surfaces.  This number sense is considered to be one of the few core capacities that animals have evolved in order to navigate and reason about the external world.