Quick facts about Centuries
By definition, centuries are defined as years 1-100.
The 20th Century started on 1 January 1901, not 1900. It ended on 31 December 2000.
Similarly, the 21st Century started on 1 January 2001, not 2000.
So 1st January 2000 was still in the 20th Century, although many of us welcomed in the 21st century at the time!
The 19th Century is from 1 January 1801 until 31 December 1900, so:
- A penny dated 1899 is 19th Century
- A penny dated 1900 is 19th Century
- A penny dated 1901 is 20th Century.
What about the first Century? That ran 1 to 100 too. Strangely, in the Anno Domini (AD) system which we use in the current Gregorian calendar, there is no year zero. You have year 1 BC and year 1 AD, but no year zero. In our calendar, 1 AD immediately follows 1 BC.
Astronomical year numbering does have a year zero as do some ISO standards, with previous years being negative, -1, -2, etc.