We count centuries that way, because we say "1st century", "20th century", "21st century". (That is, "20th century AD".) Ordinal numbers, based on the year 1 AD.
Nobody says "178th decade", or "213th decade". Decades are cardinal numbers. Nobody starts "the decade" in the 1 year.
wow rude, I do. I think the 60s started 1961-01-01 and understand that people usually mean "the years that give a quotient of 196 when divided by 10".
I understand that we use ordinals to refer to centuries, also I understand how that's unrelated to which specific years are in a decade/century/millennium
fun fact the Australian constitution came into force on the 1st of January, 1901, aligning with the starting boundary of the 20th century.
> [I] understand that people usually mean "the years that give a quotient of 196 when divided by 10".
since I'm not a pedantic sicko that gets off on telling people they're wrong and lording my hugely advanced intellect over them, I use human words for genuine natural interactions.
Since there was no 0 AD, we count decades from 1 - 10, not 0 - 9. yes that's stupid