In rain man, dustin hoffman's character performs mind-boggling feats of mathematical calculations, yet cannot perform the simplest of tasks such as determining how much change he would receive when buying a candy bar. this illustrates:

In the characteristic shown by Dustin Hoffman in the movie of Rain man, he is likely to be featuring or having savant syndrome. This enables a person to perform activities that are more exceeding to a normal or average person that are more profound but they are likely to have deficits in areas of their brain when processing such example is making simple tasks.