range as a {73,13,20} system; 73×13×20= 18980 , the number of days in the 52-year "calendar wheel" (see [12] pp. 314-315). By contrast, the " Long Count " (referenced in the movie 2012 ) is a comparatively much simpler {20,20,20,18,20} system, a cycle of 2880000 days (see [12] pp. 316-322). Residue number