“Many European languages have special words for 11 and 12 (and sometimes into the teens), which are often misinterpreted as vestiges of a base-twelve system. However, in actuality, most if not all of these terms have been eroded from decimal roots. For example, in Latin, the teens were formed by suffixing -decem (ten) to the respective words. In the modern Romance languages, this is often obscured by sound changes. For example, undecem and duodecem became, in Spanish, once and doce (likewise trece, catorce, quince) and in French, onze and douze (likewise treize, quatorze, quinze, seize from 13 until 16). English “eleven” and “twelve” are believed to come from Proto-Germanic *ainlif and *twalif (respectively “one left” and “two left”), also related to base-ten. Admittedly, the survival of such apparently unique terms may be connected with duodecimal tendencies, but their origin is not duodecimal.”

2) Douglas Adams said, on this topic, “I may be a pretty sad case, but I don’t write jokes in base 13!” (source: http://en.wikiquote.org/wiki/Douglas_Adams)

3) Good point, I hadn’t thought of this one!

And the question is, “What is six times nine?”

Therefore we see that the Universe uses base 13, at least for determining its own purpose.

The Babylons used base 60, didn’t they? If I recall correctly that’s why we still measure circles in 360 degrees–that’s what those crazy Babylon dudes used for astronomy, and so we still do today.