Short answer
How many kinds of dyscalculia are there?
The best-known classification of dyscalculia types comes from the Slovak researcher Ladislav Kosc, who in 1974 described six types: verbal, practognostic, lexical, graphical, ideognostic and operational dyscalculia. This list is historical. Modern research treats developmental dyscalculia as heterogeneous: people differ in which underlying skills are weak, such as the core sense of quantity, working memory or visuospatial skills, and many show a mix. A separate distinction is between developmental dyscalculia, present from childhood, and acquired dyscalculia (acalculia), which follows brain injury.
- Kosc (1974) described six types of developmental dyscalculia.
- The six types are verbal, practognostic, lexical, graphical, ideognostic and operational.
- Current research describes varied cognitive profiles rather than fixed types (Kaufmann et al., 2013).
- Acquired dyscalculia, or acalculia, follows brain injury and differs from developmental dyscalculia.
Search for the types of dyscalculia and you will find the same list of six names again and again: verbal, practognostic, lexical, graphical, ideognostic and operational. The list is real and still useful for describing what a person finds hard, but it is more than fifty years old, and research since then has moved on. This guide explains the six classic types, what each one looks like, and how researchers describe the different faces of dyscalculia today.
Are there really different types of dyscalculia?
Yes and no. Dyscalculia is not one uniform difficulty: two people with the same label can struggle with quite different things. One may be unable to see at a glance which of two groups is bigger; another handles quantities well but cannot hold a number in mind long enough to finish a sum; a third reads digits fluently but mixes up the operation signs. In that sense there are clearly different kinds of dyscalculia.
What research does not support is a neat set of separate types, each with its own cause, that a person either has or does not have. The difficulties overlap, they change with age and schooling, and most people show a mixture. So it helps to read any list of types as a map of the areas that can be affected, not a set of boxes.
Kosc's six types of dyscalculia (a historical classification)
In 1974 the researcher Ladislav Kosc published a study of developmental dyscalculia in the Journal of Learning Disabilities. He defined it as a structural disorder of mathematical abilities and grouped the difficulties he saw into six types, according to which part of mathematical activity was affected. The names come from that paper and are still widely quoted, especially in Spanish, Portuguese and Eastern European sources.
| Type (Kosc 1974) | What is affected | Example |
|---|---|---|
| Verbal dyscalculia | Naming and understanding numbers, quantities and maths terms in spoken language | Can read and write 7 but cannot say "seven" when shown seven objects, or does not follow "take away three" |
| Practognostic dyscalculia | Handling real or pictured objects mathematically: counting, comparing, ordering and estimating | Cannot line up sticks from shortest to longest or say which pile of blocks has more |
| Lexical dyscalculia | Reading mathematical symbols: digits, multi-digit numbers and signs | Reads 71 as 17, or reads × as + |
| Graphical dyscalculia | Writing mathematical symbols | Writes "one hundred and four" as 1004, or cannot copy digits into columns |
| Ideognostic dyscalculia | Understanding mathematical ideas and relations, and calculating in the head | Knows 7 + 5 = 12 by rote but cannot see that 12 − 5 must be 7 |
| Operational dyscalculia | Carrying out arithmetic operations correctly | Adds when the task asks for multiplication, or switches operations halfway through |
Verbal, lexical and graphical dyscalculia: the language of numbers
Three of the six types are about how numbers are expressed: said aloud (verbal), read (lexical) and written (graphical). They overlap with reading and writing skills, which is one reason dyscalculia so often occurs together with dyslexia — see dyscalculia vs dyslexia for how the two differ.
Practognostic, ideognostic and operational dyscalculia: quantity and calculation
The other three concern what numbers mean and what you do with them: working with quantities directly (practognostic), grasping relations between numbers (ideognostic) and carrying out operations (operational). Practognostic difficulties come closest to what modern research calls a core weakness in number sense.
How research describes dyscalculia types today
Since the 1970s, research on developmental dyscalculia has shifted from sorting people into types to asking which underlying cognitive skills are weak. A consensus paper that looked at dyscalculia from a developmental and differential perspective argued that it is a heterogeneous condition: the pattern of strengths and weaknesses varies between people and changes over development. Reviews in paediatrics describe the same picture.
A meta-analysis of the cognitive profile of maths difficulties, based on clinical criteria, pooled many studies to see which skills are weaker in children with maths difficulties. It found difficulties across several areas rather than in one alone — basic number processing, but also memory and other supporting skills — which again argues against a single uniform type.
Profiles also shift with age. A young child's difficulty may show mainly as trouble comparing small groups or learning the counting sequence. The same child a few years later may have caught up on counting but still be slow with number facts, place value and written sums. In adulthood the same underlying weakness tends to show up with money, time, estimating and remembering numbers. That is one more reason a fixed type assigned once in childhood says less than a regular look at which skills are currently the weakest link.
Profiles researchers commonly describe
- A core number-sense profile: difficulty representing and comparing quantities, seeing small amounts at a glance and linking digits to amounts.
- A memory profile: number sense is adequate, but number facts do not stick and working memory runs out during multi-step sums.
- A visuospatial profile: difficulty with place value, columns, the number line, clocks and geometry.
- A mixed profile: several of the above together, often alongside reading or attention difficulties (see dyscalculia examples).
These profiles are descriptions, not official subtypes either. Their value is practical: knowing which skill is weakest tells you where practice should start. Our free dyscalculia test is built around this idea, with one short game per core skill.
Developmental vs acquired types of dyscalculia
The most important distinction between kinds of dyscalculia is not between Kosc's six types but between two different origins.
- Developmental dyscalculia is present from childhood. Number skills develop differently from the start, and the difficulty usually persists into adulthood. This is what people normally mean by dyscalculia, and it is the subject of our pages on symptoms and dyscalculia in adults.
- Acquired dyscalculia, usually called acalculia, appears after number skills had developed normally, as a result of brain injury, stroke or a neurological illness. Someone who calculated easily can suddenly lose the ability to read numbers or do simple sums.
The two can look similar on a test, but the history is different, and so are the questions a professional asks. Acquired acalculia is assessed in a neurological setting; developmental dyscalculia is usually explored through school and educational psychology services.
Primary vs secondary types of dyscalculia
A second useful distinction is between primary and secondary maths difficulties. In primary dyscalculia the difficulty with numbers is the main problem and is not explained by something else. In secondary maths difficulties, poor number skills are a consequence of another cause.
| Primary dyscalculia | Secondary maths difficulties | |
|---|---|---|
| Main cause | A specific difficulty with number processing itself | Another factor: missed schooling, attention difficulties, language problems, anxiety, sensory or general learning difficulties |
| Pattern | Persistent weakness in basic number skills despite adequate teaching | Maths suffers along with, or because of, the other factor |
| What helps first | Targeted practice of the basic number skills | Addressing the underlying factor, alongside maths support |
Real cases are often mixed. A child with attention difficulties may also have a primary weakness in number sense (attention and number difficulties often occur together), and anxiety can sit on top of either. Separating the threads is part of a formal assessment, explained on how dyscalculia is diagnosed.
Types of dyscalculia in the ICD and DSM
The official classification systems do not divide dyscalculia into types at all. The ICD-10 lists a specific disorder of arithmetical skills; the ICD-11 lists a developmental learning disorder with impairment in mathematics; the DSM-5 uses a specific learning disorder with impairment in mathematics and asks the assessor to note which areas are affected and how severe the difficulty is. For the codes and what they cover, see our guide to the dyscalculia ICD-10 code.
Why the type of dyscalculia matters for support
Labels such as "graphical dyscalculia" matter less than the question behind them: which skills are weak, and which are strong? The answer shapes what to practise and in what order.
If quantity itself is weak, start with seeing and comparing small amounts, then link digits to those amounts.
If the number line is weak, practise placing and estimating numbers on a line before moving to place value and larger numbers.
If memory for facts is weak, keep practice short and frequent, and use strategies such as doubles and bridging through ten rather than rote drills.
If reading or writing numbers is the issue, work on the link between spoken, written and quantity forms of the same number.
Ideas for each of these are in our dyscalculia exercises guide. Our paid program arranges ten exercise types across 196 levels so each area can be practised daily, starting from the skill that needs it most.
Common myths about the types of dyscalculia
- "Everyone with dyscalculia has one of six types." The six types describe areas of difficulty; most people show a mixture.
- "The type tells you the cause." Kosc's types describe what is affected, not why.
- "Acalculia is just adult dyscalculia." Acalculia is acquired after brain injury; adults with developmental dyscalculia have had it since childhood.
- "If maths is weak because of something else, it isn't real." Secondary maths difficulties still need support, even if the first step is to address the underlying cause.
