25 years old now in 2025 - what year born?

Today, 18 January 2025 if a person is 25 years old now, what year was he born? See below:

If 25 years old, year of birth is:
1999 or 2000*

*It depends on whether he was born before or after 1 January 2000.

If now 25 years and his year of birth 1999 if he was born after 18 January 1999 until 31 december 1999 inclusively, and his year of birth is 2000 if he was born from 1 January 2000 to 18 January 2000.

Other examples:

If now 6 years, year of birth 2018 or 2019
If now 12 years, year of birth 2012 or 2013
If now 30 years, year of birth 1994 or 1995
If now 91 years, year of birth 1933 or 1934

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