85 years old now in 2023 - what year born?

Today, 26 September 2023 if a person is 85 years old now, what year was he born? See below:

If 85 years old, year of birth is:
1937 or 1938*

*It depends on whether he was born before or after 1 January 1938.

If now 85 years and his year of birth 1937 if he was born after 26 September 1937 until 31 december 1937 inclusively, and his year of birth is 1938 if he was born from 1 January 1938 to 26 September 1938.

Other examples:

If now 12 years, year of birth 2010 or 2011
If now 17 years, year of birth 2005 or 2006
If now 30 years, year of birth 1992 or 1993
If now 36 years, year of birth 1986 or 1987

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