The pdf is a brief discussion of the Base 60 number system and includes some problem solutions for examples. It is only 7 pages long but assumes a certain basic knowledge of numbering systems and methods of summation (using the capital Greek letter "Sigma"). The Babylonians used a "Rule of Twelve" (5 X 12 = 60) to count using fingers sort of like an abacus to count to twelve, and the other to count the "12's" to get to 60.