IIRC In the Scientific American / Scientist there was an article a few years ago about counting. The stories main line was that counting in its earliest form was "body part" based.
Even the most "primitive" civilizations understood the number 1 to 5 (fingers) Above that there was only infinity. For some others the next important frontier was 20 (fingers + toes) .
Can't find the article but a related link - http://www.es.flinders.edu.au/~mattom/science+society/lecture3.html -
This number 20 has still a separate name e.g. in French "vingt" , it is not the same grammatical construction like thirty (which derives from three-ten), in French you even have 80 called quatre-vingt 4x20.
Just to add to the confusion...
Q: how to represent negative numbers in base64? one or two complements? (is -0 an other number than +0)