<unk>  (difficulty in learning or comprehending mathematics) was originally identified in case studies of patients who suffered specific arithmetic disabilities as a result of damage to specific regions of the brain.  Recent research suggests that<unk>  can also occur developmentally, as a genetically-linked learning disability  which affects a person's ability to understand, remember, and/or manipulate numbers and/or number facts (e.g. the multiplication tables). The term is often used to refer specifically to the inability to perform arithmetic operations, but is defined by some educational professionals and cognitive psychologists as a more fundamental inability to conceptualize numbers as abstract concepts of comparative quantities (a deficit in "number sense").  Those who argue for this more constrained definition of<unk>  sometimes prefer to use the technical term Arithmetic Difficulties (AD) to refer to calculation and number memory deficits.<unk>  is a lesser known disability, similar and potentially related to dyslexia and Developmental Dyspraxia.<unk>  occurs in people across the whole IQ range, and sufferers often, but not always, also have difficulties with time, measurement, and spatial reasoning. Current estimates suggest it may affect about 5% of the population.  Although some researchers believe that<unk>  necessarily implies mathematical reasoning difficulties as well as difficulties with arithmetic operations, there is evidence (especially from brain damaged patients) that arithmetic (e.g. calculation and number fact memory) and mathematical (abstract reasoning with numbers) abilities can be dissociated.  That is (some researchers argue), an individual might suffer arithmetic difficulties (or<unk> , with no impairment of, or even giftedness in, abstract mathematical reasoning abilities.
The word<unk>  comes from Greek and Latin which means: "counting badly". The prefix "dys" comes from Greek and means "badly". "Calculia" comes from the Latin "calculare", which means "to count". That word "calculare" again comes from "calculus", which means "pebble" or one of the counters on an abacus.<unk>  can be detected at a young age and measures can be taken to ease the problems faced by younger students. The main problem is understanding the way mathematics is taught to children. In the way that dyslexia can be dealt with by using a slightly different approach to teaching, so can<unk> . However,<unk>  is the lesser known of these learning disorders and so is often not recognized.
Another common manifestation of the condition emerges when the individual is faced with equation type of problems which contain both integers and letters (3A + 4C).  It can be difficult for the person to differentiate between the integers and the letters.  Confusion such as reading a '5' for an 'S' or not being able to distinguish between a zero '0' for the letter 'O' can keep algebra from being mastered.  This particular form of<unk>  is often not diagnosed until middle or high school is entered.
Dyscalculia
Acalculia
Penis enlargement
Acanthosis nigricans
Acral nevus
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Xerosis
Dyspareunia