Please tell me the types of mental retardation.?

Several levels: Broadly, mr is divided into mild, moderate, severe, and profound, contrasting actual function to chronological age. For a 10 yo, mild mr is 5-7 yo; for moderate mr, 3-5 yo; for severe mr, 2-4 yo; and for profound mr, 1-2 yo. This is not always precise--some may be stronger is some areas an weaker in others. Also, the more severe the mr, the quicker the child reaches maximum performance levels.