Dyscalculia is a mathematical disability that affects a persons ability to perform arithmetical skills, learn, or comprehend mathematics. It is a lifelong learning disability that involves difficulties with math at many levels. People with dyscalculia may have trouble counting, arranging things in order or sequence, understanding fractions, using steps in a mathematical operation, understanding concepts of quantity, place value, and positive and negative values, and adding, subtracting, multiplying, or dividing. Dyscalculia is associated with difficulty in arithmetical skills. Brain imaging studies have shown some differences between people with and without dyscalculia, which have to do with how the brain is structured and how it functions in areas that are linked to learning skills. Researchers are trying to learn if there are strategies that can help "rewire" the brain to make math easier.