> 
>I think:
>    that the first decade consisted of the years  I - X,
>    that the first century consisted of the years I - C,
>and that the first millenium consisted of the years I - M
>(everything A.D and in Roman notation).  Thus my new sig file:
>Hans Dinsen-Hansen    http://www.danbbs.dk/~dino/
>                      mailto:dino@danbbs.dk
>If Jan. 1st 2000 is the start of a new millennium:
>   - Which millenium had 999 years?
>   - i.e. which century had 99 years?
>   - i.e. which decade had 9 years?
You are correct.  instead of starting at year 0 the Romans started at one.  Why?  The Romans didn't use zero in their number system.  Most people don't know this and make the assumption that every year ending with 0 is instantly a new decade/century/millenium.

I.e. a new born child is not a 1 year old, we refere to the childs age in days, weeks and months.  The Romans just jumped to year 1!

So we are still in the 10th decade of the 20th century in the 2nd millenum.

So I can't wait to see what industries have in store for us; "1999-2000 New Years was great, but the real New Year Millenium (2000-2001) will be even bigger!  So hurry and get your <insert product> before they're gone!"