
 The First PlaceValue Number System 
  And so we come to the Babylonians, who were famous for their astrological observations and calculations, and who used a sexagesimal (base60) numbering system (see also The invention of the abacus). 
  sexagesimal system, which first appeared around 1900 to 1800 BC, is also credited as being the first known placevalue number system, in which the value of a particular digit depends both on the digit itself and its position within the number. 
  This was an extremely important development, because prior to placevalue systems people were obliged to use different symbols to represent different powers of a base, and having unique symbols for ten, onehundred, one thousand, and so forth makes even rudimentary calculations very difficult to perform (see also The Ancient Egyptians). 
 www.maxmon.com /1900bc.htm (315 words) 
