17 years old now in 2025 - what year born?

Today, 19 December 2025 if a person is 17 years old now, what year was he born? See below:

If 17 years old, year of birth is:
2007 or 2008*

*It depends on whether he was born before or after 1 January 2008.

If now 17 years and his year of birth 2007 if he was born after 19 December 2007 until 31 december 2007 inclusively, and his year of birth is 2008 if he was born from 1 January 2008 to 19 December 2008.

Other examples:

If now 9 years, year of birth 2015 or 2016
If now 14 years, year of birth 2010 or 2011
If now 22 years, year of birth 2002 or 2003
If now 51 years, year of birth 1973 or 1974

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