Arithmetic disorder, also known as dyscalculia, is considered a developmental disorder that causes sufferers to have extreme difficulty in the use and manipulation of numbers, time, and spatial reasoning. It is is an inborn difficulty, a problem within the "mental wiring" that is believed to effect 3-6% of the population. The parietal lobe is believed to be associated with this disorder. Individuals with this disorder can find it difficult to perform even the most basic mathematic tasks such as simple addition and subtraction. A similar disorder called acalculia is an acquired disability and is often the result of brain injuries.