When does the decade end?

Answer 1

11:59:59.9 PM, December 31, 2009.

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I don't agree.

The first year was the year ' 1 ', not ' 0 '. That's why the end of the first Century (100 years)

was the end of the year ' 100 ', and the end of the 20th Century was the end of ' 2000 '.

By definition, a decade is 10 years. The first decade consisted of the years [ 1 - 10 ], and ended

at the end of the year ' 10 '. Add 10 years to that for every subsequent decade, and eventually

you wind up in our current era. The ends of decades occur at 11:59:59.9 PM on December 31st

of 1990, 2000, and 2010.

If you accept the reasoning concerning the Century but not concerning the decade, then you

wind up in an awkward position, with the year 2000 being in the old Century but the new decade.

Wikipedia resolves this problem by only having "9" years in the first "decade".

The new decade does not start until Jan. 1, 2011 , one second past midnight on Dec 31st, 2010.

When you refer to the "60's" you are refering to the years 1960 to 1969, ten years... just not the same as the decade of the 60's.