Welcome to the year 2000 the last year of the 2nd Millennium

When closing the year long party next Dec 31, 2000 we will

begin on Jan 1, 2001 the begining of the 3rd Millennium

All you math experts why are we leaving the 20th Century & entering the

21st century. If I count correct 20 comes befor 21

We should be leaving the 19th century entering the 20th century