The human brain under normal circumstances displays but a small portion of its capabilities. The true range of any one capability is disguised by the need to enlist many capabilities at once, hundreds, in fact. Like a traffic cop handling the flow of traffic on multiple intersections, all with differing rules and timing and speeds, the normal brain activity interrupts any given thought process so that it barely starts before it stops. If, on the other hand, the traffic cop has but one lane to manage, there would be no interruption, and a vehicle on that road could start and not stop until at its destination. Therein lies the reason some autistics appear incredibly gifted. They have but a single traffic lane clear, from beginning to end. Those autistics who entertain more traffic, whether this is evident to those observing them or not, appear to be simply autistic.
Thus, an autistic who has never spoken or glanced at flash cards held before him or lifted a spoon or fork to feed themselves may be able to sit at the piano and play a complex piece, having only had the opportunity to observe an experienced pianist play that piece a single time. Likewise, autistics who have integrated the digital or binary or any other type of number system can compute as fast as a calculator or computer the results of equations that require thousands of steps, as long as those steps do not require more than one traffic lane. Complex concepts, involving multiple traffic lanes, receive the same blank, apparently uncomprehending, stare from autistics that is their normal response.