Except, of course, it was not in two different centuries. The 20th century started January 1st 1901. Not January 1st 1900. 1900 was the last year of the 19th century. You don't start counting at zero. 20 is not the first number of the twenties, but is the last number of the teens. 50 is not the first number of the 50s but is the last number of the 40s.
And two plus two is four. I have to throw that in because there's so many people out there that don't know diddly about arithmetic.