Issues of mental representation are central to cognitive psychology an
d indeed to psychology in general. This article synthesizes recent the
oretical and empirical research concerning cognitive representations i
n one specific domain, that of numbers. First, several forms of cognit
ive numerical representation are defined, and the roles the various fo
rms may play in numerical processing are considered. Then, two current
representational issues that have generated some controversy are exam
ined: In what form are arithmetic table facts (e.g., 4 x 7 = 28) store
d in memory, and what forms of representation are involved in converti
ng numerals from one form to another (as in reading 604 aloud as ''six
hundred four'')? In the course of the discussion the major current th
eories of numerical cognition are described, with emphasis on how they
differ in their assumptions about numerical representations and how t
hese differences are reflected in the positions taken on various speci
fic issues.