Historically, few researchers have given much thought to the cognitive role of the objects used to represent and manipulate numbers. We aren’t used to thinking of material devices as being a meaningful part of our cognition, and as a result, we are literally blind to them. This makes it difficult to recognize that the material forms used in numbers influence how and what we think about them. Nonetheless, variability in cultural number systems is a matter of whether material forms are used, which ones are used, and how they are used. Material forms like fingers, tallies, tokens, and written numerals are the key to cross-cultural numerical variability because, as a single species, everything else that contributes to numbers is the same. Despite our profound neurological, physiological, and behavioral similarity, not all human societies count, and of those that do, not all count in the same way. This variability suggests that humans don’t come pre-equipped with internal instructions for realizing and then structuring and organizing their numbers. The conclusion ends with a list of questions that researchers in different fields might ask in response to the cross-cultural variability found in number systems.