How to calculate the birth year?

The animal year algorithm is as follows

According to the year (animal year): 12 years old, 24 years old, 36 years old, 48 years old, 60 years old, 72 years old, each plus 12 years old is your own animal year.

According to nominal age (animal year): 13 years old, 25 years old, 37 years old, 49 years old, 6 1 year old, 73 years old is also 12 years old, but the base numbers are different.