<Dl> <Dd> mental age ÷ Physical age × 100 = IQ </Dd> </Dl> <Dd> mental age ÷ Physical age × 100 = IQ </Dd> <P> No matter what the child's chronological age, if the mental age is the same as the chronological age, then the IQ will equal 100 . </P> <P> Modern intelligence tests, including the current Stanford - Binet test, no longer compute scores using the IQ formula . Instead, intelligence tests give a score that reflects how far the person's performance deviates from the average performance of others who are the same age, arbitrarily defined as an average score of 100 . </P>

How to calculate the mental age of a child