The human brain is an extremely complex organ, capable of a wide variety of different kinds of processing skills such as thinking abstractly, generalizing concepts, discerning patterns in information, understanding metaphor, articulating ideas, and drawing inferences. Each of us is different in our competence in each of these domains. IQ is a measure that gives us an average of our skills across these cerebral skills. Consequently, two people who have the same IQ, could have a very different set of strengths and weaknesses across these domains. If you were to administer a mathematical aptitude test to 100 people with IQ 130 you would find a great variation in their test scores.