Psychology uses "intelligence quotient" or "IQ" to express a person's intelligence level. The usual algorithm of IQ is "psychological age ÷ actual age ×1". According to the research, the intelligence level can be divided into seven grades: 1. Genius with IQ greater than 14, excellent intelligence between 12 and 14, excellent intelligence between 11 and 12, average intelligence between 9 and 11 (most people), low intelligence between 8 and 9, and some defects between 7 and 8.