How Common is Dyscalculia?

Patient Presentation
An 11-year-old male came to clinic for his health supervision visit. He was doing well playing soccer, reading books and occasionally playing some videogames with his siblings and friends. His mother brought up that he had always struggled with math and was slower in reading. They had gotten him a tutor but last academic year he was falling farther behind. They had him evaluated by a private psychologist who diagnosed him with a specific learning disability in math and with a weakness in reading. He was doing well socially and was well-liked by friends and teachers. The mother stated, “We have gotten him a different tutor now and are going back to basics. Lots of repetition about things, using a calculator, and trying to figure out work arounds. He can remember his street address but always messes it up when he has to write it. We just put his address on a card in his backpack and he can use if he needs it.” The past medical history was non-contributory. The family history was positive for his father who also had “problems with math and reading.”

The pertinent physical exam showed a well-mannered talkative boy with normal growth patterns and vital signs. His examination was normal. The diagnosis of a healthy boy with a specific learning disability in math was made. The pediatrician asked if the mother had already contacted the school about the problem. “Oh yeah, they know and are being pretty good about helping. He already is getting help specifically in math but his teacher understands it’s a bigger problem and so is helping him during the rest of the day. He has a hard time understanding time. For example, she knows that he doesn’t understand that he might have to stop at 3:00 o’clock and will make sure he knows that is about 10 minutes time or half of recess time.”

Numerical understanding is imperative in everyday life. Even making coffee in the morning, a person considers whether she is making 1 cup or 2, and how much fluid will be in each cup. How many more days can she go without buying more coffee with the ground coffee left in the container? Other numerical skills such as telephone numbers, street addresses and locations, time and dates, and buying and selling of products and services occur all day long in people’s lives. What happens when those skills are not automatic?

Dyscalculia or developmental dyscalculia (DD) is “a heterogeneous learning impairment affecting numerical and/or arithmetic functioning at behavioral, psychological and neuronal levels.” It can also be defined as a “…domain-specific learning disorder that emerges at an early stage of development and cannot be explained by inappropriate schooling or deficient learning opportunities.” It can also be defined as a specific learning disorder. Specific learning disorders such as dyscalculia, reading or writing are “… a neurodevelopmental disorder of biological origin manifested in learning difficulties and problems in acquiring academic skills markedly below age level and manifested in the early school years, lasting for at least six months, not attributed to intellectual disabilities, developmental disorders, or neurological or motor disorders.” DD is not a term to be used for all forms of mathematical difficulties and is used for those who are severely impaired. Other terms for DD are math learning disability, acalculia, math anxiety, numerical impairment, and non-verbal learning disorder.

DD is a very heterogeneous disorder and this makes the definition and the research studies more difficult. DD is persistent into adulthood and females may be more affected than males but the studies are inconsistent. DD co-morbidities are common and include attention problems, anxiety, dyslexia, depression, spatial working memory problems and visual-spatial impairments for example.

Some examples of the development of numerical processing skills includes:

  • Basic skills include innate number sense (e.g. discerning between small quantities with greater distance), quantity discrimination skills (larger quantities, smaller distances) and subitizing. Subitizing is a basic numeric capacity where the person is able to perceive and conceptualize small quantities. In preschool children this is up to three in adults this is usually around five. People with DD have problems in 1 or more areas.

  • Number skills include mapping different numerical representations (e.g. actual quantity (***), number words (three), Arabic digits (3)), counting, place-value systems and mental number line representations (e.g. linear functions < logarithmic function). People with DD have problems such as inaccurately transferring information from one context to another. For example, the patient sees *** and write two or 2.
    Or is told 762 and writes down 700602.
    They also have problems with understanding place-value system. For example, the number is 65 but patient does not understand that the number 6 represents 6 groupings of 10.

  • Calculation skills include math by counting (i.e. 1,2,3,4,…), retrieval (e.g. math facts 2×2=4), decomposition (e.g. representing same idea in different ways (5*8 = 4*10 = 36 + 4 = 40), and learning different calculation procedures and concepts.
    For people with DD, they may have no way to recall math facts and thus may need to work each problem individually which can be very tiring and time consuming.
    For example, patients may not know 3*3 = 9, but can say to themselves, “This means 3 groups of 3, so if I add 3 plus 3 plus 3 this is 9.” Calculations and procedures can be especially troublesome.

Interestingly, functional brain imaging shows a complex fronto-parietal neuronal network at work with mathematical concepts. With development there is more focal recruitment of brain areas (more towards the parietal lobes) and less on supporting general brain function (more in the frontal lobes). In people with DD, the patterns are less precise and there is recruitment of other brain areas such as those involved with attention, working memory and monitoring.

Current interventions include individual training, repetition, and working on curricular and non-curricular numerical topics. Help for co-morbidities is important. Some other daily life interventions include use of calculators for routine math facts, using graph paper to help with organization of the numbers into columns, or separating money into different piles (so someone doesn’t confuse a $1 with a $10 which look alike). Street addresses can be programmed into cellphones with driving instructions given verbally when someone is actually driving. Calendars, timers, and automatic alarms are often helpful to remind people about time issues. Working with others to double-check someone’s math, is helpful for almost everyone and especially helpful for someone with DD. Using people’s strengths to support their weakness is also important. For example, someone with better verbal or memory skills may rehearse an address over and over.

Learning Point
It is estimated in a United Kingdom study that 22% of adults have some type of mathematical difficulty that causes occupational or practical problems.
DD with its more restrictive definition has a prevalence rate of 3-6%.

Questions for Further Discussion
1. What is the definition of dyslexia and how common is it?
2. What is an individualized education plan?
3. What is a 504 plan?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Learning Disabilities

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Kaufmann L, Mazzocco MM, Dowker A, von Aster M, Gobel SM, Grabner RH, Henik A, Jordan NC, Karmiloff-Smith AD, Kucian K, Rubinsten O, Szucs D, Shalev R, Nuerk HC.
Dyscalculia from a developmental and differential perspective. Front Psychol. 2013 Aug 21;4:516.

Kucian K, von Aster M. Developmental dyscalculia. Eur J Pediatr. 2015 Jan;174(1):1-13. Available from the Internet at (cited 11/13/18).

Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa