Well, for South Koreans, that’s exactly what’s happened when the country changed it's age laws. The first, known as international age, uses the conventional age system where a baby is zero months old when it is born. This is a mash-up of international age and Korean age. He's 45 according to international age, 46 according to Korean age and 47 according to the mixed method. It's unclear how the Korean age system came about.

Source: The Guardian June 29, 2023 17:25 UTC