Why do fortune tellers like to say children 15 years old?

Fifteen years old has no special significance except going to school or studying. It should be a carefree age. Ancient people had a special name for age, and fifteen years old was a year of study. The Analects of Confucius: Confucius said, "Five out of ten people are determined to learn ... At the age of fifteen, an ancient woman combed her hair and put on a kind of jewelry called a necklace.