A century is a period of 100 years. A millennium is a period of 1000 years. The first year in our calendar was year 1. Press the button to find out if you were right. Press the button to find out if you were right.
Centuries Now let's look at centuries.
Press the button to find out if you were right. Millenniums Now for millenniums. Press the button to find out if you were right. Press the button to find out if you were right. Now you are ready to work out whether the next millennium begins in 2000 or 2001.