Here we say something like the "ninteen-hundred-era" for the 1900s, "ninteen-hundred-ten-era", for 1910s, "ninteen-hundred-twenty-era", etc. In writing 1900-era

Here we say something like the "ninteen-hundred-era" for the 1900s, "ninteen-hundred-ten-era", for 1910s, "ninteen-hundred-twenty-era", etc. In writing 1900-era, 1910-era, 1920-era. The most recent decades are referred to with only the "70-era" for the 70s. The word for age/epoch/era in our language is a lot more casual in this setting. The 20xx vs 200x does indeed leave some room for ambiguity in writing, verbally most people say 20-hundred-era vs 20-null-null-era.