Answers (2)
See,
1-100 was the 1st century,
101-200 was the 2nd century (even though you might think it would be the 1st)
201-300 was the 3rd century (even though you might think it would be the 2nd)
and so on.
When we reached the year 2000, we already went through 20 centuries, which would be why today (after the 2001st century) would by the 21st century. Hope this helped.
There was no year zero. So from 1 AD to 1BC was only one year. From 1 to 100 was the first century. From 101 to 200 was the second century. And so on. The new millennium was actually a year after they celebrated it, Jan 1 2001 rather than Jan 1 2000.
To complicate matters even more, our calendar is 300 years off. There was no "dark age" in Europe.
www.cl.cam.ac.uk/~mgk25/volatile/Niemitz-1997.pdf
These things come about because people are generally lousy at arithmetic.
Oops, I meant "(after the 2001st year)".