113 years old now in 2023 - what year born?

Today, 26 September 2023 if a person is 113 years old now, what year was he born? See below:

If 113 years old, year of birth is:
1909 or 1910*

*It depends on whether he was born before or after 1 January 1910.

If now 113 years and his year of birth 1909 if he was born after 26 September 1909 until 31 december 1909 inclusively, and his year of birth is 1910 if he was born from 1 January 1910 to 26 September 1910.

Other examples:

If now 5 years, year of birth 2017 or 2018
If now 18 years, year of birth 2004 or 2005
If now 18 years, year of birth 2004 or 2005
If now 52 years, year of birth 1970 or 1971

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