I. Basic Concepts Numeracy is a very complex cognitive process that requires the involvement of cognitive components such as language, visual perception, space, memory, attention, and executive function. Brain lesions that result in the loss of the ability to perform computational tasks are called dyscalculia or technologically acquired computing disorder. Dyscalculia commonly occurs in dementia and limited brain lesions (i.e., stroke, traumatic brain injury, etc.). It can be manifested as loss of understanding of written numbers (i.e., loss of reading of numbers), spatial impairment leading to inability to correctly align numbers in written calculations, inability to extract or use arithmetic facts, and primary loss of arithmetic concepts. Second, the classification of miscalculation disorders Miscalculation disorders are divided into two categories: primary miscalculation disorders and secondary miscalculation disorders. Primary alexia is classified as a primary impairment of arithmetic ability; secondary alexia arithmetic arises from other cognitive dysfunctions (e.g., language, memory disorders, etc.) and is secondary to impairments in a variety of verbal, spatial, and executive functions, such as aphasic alexia, dyslexia, dyscalculia, frontal alexia, and spatial alexia. In fact, these types of aphasia overlap to some extent, and primary aphasia is often combined with aphasia, dyslexia, and dysgraphia. Clinical manifestations of secondary aphasia Patients with aphasia often have difficulty with arithmetic, which is associated with impaired language. Patients with Wernicke’s aphasia show verbal memory impairment during number calculation, and patients with Broca’s aphasia may have difficulty with the grammar of calculation. Patients with conductive aphasia make many errors in both mental and written arithmetic tasks, and dysarthria can affect consecutive arithmetic (e.g., 2 consecutive plus 3) and counting in reverse order. Patients with alexia (i.e., parietal-temporal lobe loss of reading, or loss of reading with loss of writing) are unable to read numbers or mathematical symbols in books. This is usually characterized by a severe impairment in written arithmetic and a relatively good ability in mental arithmetic. Pure dyslexia (occipital dyslexia, or dyscalculia without dyscalculia) is characterized by a significantly poorer ability to read multi-digit numbers than single digit numbers, poor written arithmetic skills, and an inability to successfully arrange numbers and round numbers. Patients with loss of writing are unable to write number words resulting in impaired ground calculation. Frontal lobe damage, which manifests itself in the wrong sequence of calculation processes, impaired ability to understand and solve mathematical applications, etc. Patients with prefrontal lobe damage can show severe difficulties in the following computational tasks: mental arithmetic, sequential operations (especially inverse operations, such as subtracting 7 from 100 consecutively) and solving multi-step mathematical problems. Such patients show an inability to maintain focus on the current computational task and to answer questions quickly without careful consideration; to give the same answer to different problems and to read and write unneeded repetitive numbers; and to analyze complex mathematical problems and solve them using arithmetic. Patients can retain relatively good basic arithmetic skills, with better written visual than mental arithmetic. Patients with right hemisphere damage can experience spatial miscalculation, often accompanied by semispatial neglect, spatial loss of reading and writing, structural deficits, and other spatial deficits. Patients often miss numbers when reading numbers, reverse numbers, and class patients experience generalized difficulty writing numbers, misalignment of space during written calculations, and arithmetic confusion. The arithmetic confusion leads to the patient’s inability to discern the wrong result. Patients with spatial miscalculation have better mental calculation performance than written calculation. The assessment of miscalculation includes two major parts: number processing and number calculation. Number processing refers to the understanding of numbers and the generation of numbers; computational ability includes the recognition of arithmetic forms, knowledge of arithmetic, and the execution of arithmetic procedures. Therefore, the examination should include number sequences, counting of dots, numerical code conversion, calculation of symbols, comparison of sizes, simple fact extraction, operations by rules, mental and written arithmetic, and general mathematical knowledge.