Why not be one year old after fortune telling?

In China tradition, there is a saying that there is a nominal age. Imaginary age is a method of remembering age relative to real age (collectively referred to as one year old). Nominal age is a traditional way of counting age in China, and it is also very popular in other East Asian countries. Used to calculate the sequence (ordinal number) of the years that a person is experiencing after birth, which is based on the year when he was born, because this is the first year after birth, and it has nothing to do with the pregnancy time he experienced. It is different from the commonly used age calculation method in the world. It calculates the elapsed time after birth based on the zero age at birth, so it can also calculate the mantissa, such as three years and two months, seven and a half years and so on. In China, in order to distinguish between two ways of calculating age, there are two names: nominal age and full age.