Recently, on an outing with my scout troop, the question came up of when the new millenium will begin--January 1st 2000 or 2001.
So the Scoutmaster explained that each century begins with year "1" and ends with year "100"-thus the reason why the 20th century began at the start of 1901 and will end at the close of 2000.
To illustrate his point, he gathered 15 berries and asked the boys how many he had.
Each boy correctly answered "15".
His next question was, "Now which berry is number '0'?"
To which one boy blurted out, "The one that isn't there!"