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For example the word Dyslexia is as a general term for disorders that involve difficulty in learning to read or interpret words, letters, and other symbols.
Similarly is there a general term for disorders that involve inability to understand & interpret arithmetic calculations?
The term you want is dyscalculia
Severe difficulty in making arithmetical calculations, as a result of brain disorder. (Oxford Dictionary Online)
A fuller definition from the British Dyslexia Association runs
Developmental Dyscalculia (DD) is a specific learning disorder that is characterised by impairments in learning basic arithmetic facts, processing numerical magnitude and performing accurate and fluent calculations.
