Smart. Gifted and intelligent, they are gifted children, but they will regress after going to school. At the age of five, they haven't learned arithmetic, but they can add, subtract, multiply and divide, which is determined by the brain structure. After school, the addition, subtraction, multiplication and division taught by teachers are completely different from their natural methods, and they will be fooled. There is no denying that children must not be taught addition and subtraction within 20 minutes, but they must be taught in a professional way suitable for children.