10 years old now in 2025 - what year born?

Today, 19 December 2025 if a person is 10 years old now, what year was he born? See below:

If 10 years old, year of birth is:
2014 or 2015*

*It depends on whether he was born before or after 1 January 2015.

If now 10 years and his year of birth 2014 if he was born after 19 December 2014 until 31 december 2014 inclusively, and his year of birth is 2015 if he was born from 1 January 2015 to 19 December 2015.

Other examples:

If now 8 years, year of birth 2016 or 2017
If now 14 years, year of birth 2010 or 2011
If now 19 years, year of birth 2005 or 2006
If now 46 years, year of birth 1978 or 1979

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