70 years old now in 2025 - what year born?

Today, 23 January 2025 if a person is 70 years old now, what year was he born? See below:

If 70 years old, year of birth is:
1954 or 1955*

*It depends on whether he was born before or after 1 January 1955.

If now 70 years and his year of birth 1954 if he was born after 23 January 1954 until 31 december 1954 inclusively, and his year of birth is 1955 if he was born from 1 January 1955 to 23 January 1955.

Other examples:

If now 12 years, year of birth 2012 or 2013
If now 12 years, year of birth 2012 or 2013
If now 20 years, year of birth 2004 or 2005
If now 45 years, year of birth 1979 or 1980

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