I don’t think there is any debate over the fact that the year 1 BC directly preceded the year 1 AD. Leaving aside the basis in Christ’s birth and the possible inaccuracies that introduces, much of the world has been in agreement for hundreds of years that this particular trip we are beginning around the sun shall be numbered 2010.

Call it “twenty ten”, “two thousand and ten” or even, for our American friends, “two thousand ten” and you cannot escape that at the completion of the 2010th year, a whole number of decades will have passed since the cusp between BC and AD.

Therefore, the phrase “the end of the decade” shall refer to midnight on the evening of December 31st, 2010. NOT December 31st, 2009. Granted, the latter date is the end of a decade, as is that date in any year, or indeed any date you choose to subtract 10 years from. But the end of the decade comes with an assumption. That assumption is the basic concept of “since the beginning”. The 201st decade of anno domini shall be complete at the end of 2010.

While we’re on the subject, the new millenium began on January 1st, 2001.

It seems to me that the fascination of more than one digit changing (and especially all four in 2000) draws society’s attention away from basic numeracy.