Summing-up dyscalculia


Judy Hornigold explains how to identify and support dyscalculia in the classroom

If you can’t read or write well, it’s a major issue. In Britain, so many of our opportunities in life are decided by how we access the written word and how we articulate our thoughts and ideas on paper. Saying “I’m bad at reading” or “I struggle with writing” brings up lots of questions about someone’s wider abilities. So, if a child is lagging behind in literacy, we take it seriously and if we suspect dyslexia is the root cause, we have established ways to diagnose and provide effective tailored support. 

However, saying “I’m bad at maths” is common and carries little judgement about someone’s wider abilities. Generally, children are told not to worry, muddle through maths exams and focus their energy elsewhere. Hence, dyslexia’s numerical cousin dyscalculia is rarely diagnosed and not generally understood or supported – although it can cause substantial challenges that extend beyond the maths classroom. 

Dyscalculia is a specific learning difficulty with mathematics, primarily arithmetic. It is estimated to affect five percent of the population, so around half the number that are affected by dyslexia (around ten to 15 per cent of people). 

The British Dyslexia Association has recently published this definition: “Developmental dyscalculia is a specific and persistent difficulty in understanding arithmetic and basic number sense. It may also affect retrieval of number facts and key procedures, fluent calculation and interpreting numerical information. It is diverse in character and occurs across all ages and abilities. Dyscalculia is an unexpected difficulty in maths that cannot be explained by external factors. 

“Maths difficulties are often thought of as a continuum, not a distinct category, with dyscalculia at the extreme end of this continuum. It should be expected that developmental dyscalculia will be distinguishable from general maths difficulties due to the severity of difficulties with symbolic and non-symbolic magnitude, number sense and subitising. 

“Developmental dyscalculia can often co-occur with other specific learning difficulties, such as dyslexia, dyspraxia and attention deficit hyperactive disorder.”

What might suggest someone is dyscalculic?

To follow are a few key indicators that a person may have dyscalculia, rather than just being bad at maths.

An inability to subitise even very small quantities

The word “subitise” comes from the Latin word “subito” which means suddenly. It refers to our ability to immediately recognise the number of items in a set without actually having to count them. Most people can subitise up to six or seven items. A dyscalculic learner will not be able to do this and may have difficulty in subitising just three items.


Most people will instantly recognise that there are five dots here without having to count them.


However, we would have to count these dots.


A dyscalculic person may not be able to subitise even two dots.

Assessing numerical quantity 
When given two numbers, a dyscalculic learner will have difficulty in identifying which is the larger.

Poor number sense
Number sense refers to how well we can work with numbers, how they can be broken up or joined together and how we can make numbers work for us, through using them flexibly. For example, someone with good number sense would tackle 39 + 40 + 41 as 3 x 40, since this is quicker and more efficient than adding 39 + 40 + 41.

Inability to generalise
Being able to generalise greatly reduces the load on our working memory and enables us to make connections and predictions in maths. It is really a question of using what you do know to find out what you don’t know. So, if I know that 7 + 3 = 10, I can generalise this to know that 10 – 7 = 3 or 30 + 70 = 100 and so on.

Other indicators of dyscalculia:

  • an inability to estimate whether a numerical answer is reasonable
  • immature strategies – for example, counting all instead of counting on
  • poor recall of number facts and procedures 
  • difficulty in learning to tell the time, which can persist in learners with dyscalculia; they can also have difficulty with appreciating the passage of time, so they may not be able to tell whether one minute or one hour has passed
  • difficulty using money; this can be a severe difficulty and often stems from a lack of understanding of place value – for example, not being able to appreciate that a £20 note will be sufficient to cover a £15.75 taxi fare.

Screening for dyscalculia

It may be necessary to have a formal identification of dyscalculia in order to access the right kind of support and intervention. The first step would be to carry out a checklist to see if the learner is at risk and these are available from a wide range of organisations.

There are also several dyscalculia screeners that will assess the learner’s ability to subitise, to identify the numerically larger number from a pair of numbers and to perform simple calculations. Screeners can be online or pen and paper and can give very useful information about the difficulties that a particular individual has. 

The next step in identification would be a formal diagnosis and this can be carried out by a specialist assessor or an educational psychologist. However, It is important to weigh up the cost of the assessment against the benefits to the learner

How does dyscalculia affect people? 

Depending on the severity, the impact of dyscalculia is far reaching and can profoundly affect daily living. 

In extreme cases, some dyscalculic adults never learn to drive, because of the numerical demands of driving and map reading (although satellite navigation can help a great deal here). Dyscalculia can also lead to social isolation, due to an inability to be at the right place at the right time, or to understand the rules and scoring systems of games and sports. Most commonly though it leads to financial challenges due to difficulty in budgeting. 

To have dyscalculia can be a very frustrating experience, but it does not mean that you will never achieve in life. It is, after all, a specific learning difficulty. Paul Moorcraft’s book It just doesn’t add up is testament to what can be achieved despite having severe dyscalculia.  

Practical ways to support children with dyscalculia at school

  1. Use tangible materials, such as Cuisenaire rods or base ten materials; spend time exploring these and don’t take them away too soon as they will help to develop the child’s understanding.
  2. Play games with dice and dominoes so that the child can recognise common dot patterns.
  3. Encourage the child to use more efficient calculating strategies, such as counting on rather than counting all.
  4. Encourage the child to visualise the maths by drawing diagrams and using concrete materials to model the maths.
  5. Make the maths practical and multi-sensory and avoid worksheets.
  6. Spend time on place value so that it is fully understood, as this can be a very difficult concept to grasp.
  7. Have a little and often approach; repetition and overlearning will help.
  8. Use mathematical language as much as possible and encourage the child to do the same.
  9. Give multiplication grids and number bonds to reduce the stress of having to remember these facts.
  10. Courses to become specialist teachers for dyscalculia are also available; whilst many are relatively new, the hope is that over time, dyscalculia will be supported in a similar tailored way to dyslexia. 

About the author

Judy Hornigold is a member of the British Dyslexia Association’s Dyscalculia Committee and an independent education consultant specialising in dyslexia and dyscalculia:

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