13 years old now in 2025 - what year born?

Today, 24 April 2025 if a person is 13 years old now, what year was he born? See below:

If 13 years old, year of birth is:
2011 or 2012*

*It depends on whether he was born before or after 1 January 2012.

If now 13 years and his year of birth 2011 if he was born after 24 April 2011 until 31 december 2011 inclusively, and his year of birth is 2012 if he was born from 1 January 2012 to 24 April 2012.

Other examples:

If now 10 years, year of birth 2014 or 2015
If now 18 years, year of birth 2006 or 2007
If now 20 years, year of birth 2004 or 2005
If now 80 years, year of birth 1944 or 1945

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