sixty, seventy, eighty
This house was built seventy years ago.
It cost seventy pounds. (Key English Test; A2; Spanish)
Both my parents are in their seventies.
After some minutes, an old man in his late seventies opened the door and told us in his trembling voice that Daisy wasn't at home. (First Certificate in English; B2; Italian)
I grew up in the seventies.
The nineties is, indeed, a reverse of the seventies. (First Certificate in English; B2; Swedish)