I find it confusing as well: the century already has a different name and the decade does not, so it’s natural to assume “the 1900s” refers to the decade.
Also, I guess technically “the 1900s” includes 1900 but not 2000 and “the 20th century” includes 2000 but not 1900.
I find it confusing as well: the century already has a different name and the decade does not, so it’s natural to assume “the 1900s” refers to the decade.
Also, I guess technically “the 1900s” includes 1900 but not 2000 and “the 20th century” includes 2000 but not 1900.