20 years old now in 2024 - what year born?

Today, 15 October 2024 if a person is 20 years old now, what year was he born? See below:

If 20 years old, year of birth is:
2003 or 2004*

*It depends on whether he was born before or after 1 January 2004.

If now 20 years and his year of birth 2003 if he was born after 15 October 2003 until 31 december 2003 inclusively, and his year of birth is 2004 if he was born from 1 January 2004 to 15 October 2004.

Other examples:

If now 5 years, year of birth 2018 or 2019
If now 18 years, year of birth 2005 or 2006
If now 30 years, year of birth 1993 or 1994
If now 59 years, year of birth 1964 or 1965

HTML code:

BB code: