40 years old now in 2023 - what year born?

Today, 29 May 2023 if a person is 40 years old now, what year was he born? See below:

If 40 years old, year of birth is:
1982 or 1983*

*It depends on whether he was born before or after 1 January 1983.

If now 40 years and his year of birth 1982 if he was born after 29 May 1982 until 31 december 1982 inclusively, and his year of birth is 1983 if he was born from 1 January 1983 to 29 May 1983.

Other examples:

If now 6 years, year of birth 2016 or 2017
If now 16 years, year of birth 2006 or 2007
If now 29 years, year of birth 1993 or 1994
If now 64 years, year of birth 1958 or 1959

HTML code:

BB code: