The Government is failing to support more than a quarter of a million primary school children with a condition that leaves them unable to do arithmetic, according to a major study.
Urgent investment in specialist teaching is needed to improve the education of pupils suffering from dyscalculia, the mathematical equivalent of dyslexia, according to the research.
The current failure to take the condition seriously in schools is comparable to the way "dyslexics were labelled stupid back in the 1980s", according to report co-author Professor Brian Butterworth, of University College London.
"Dyscalculia is at least as much of a handicap for individuals as dyslexia and is a very heavy burden on the state, with the estimated cost to the UK of low numeracy standing at #163;2.4 billion," said Professor Butterworth.
"Nevertheless, there are only cursory references to the disorder on the Department for Education website - no indications are offered for help either for learners, teachers or parents. It's as if the Government does not want to acknowledge its existence."
Up to 7 per cent of the general population are estimated to suffer from dyscalculia, equivalent to around 280,000 primary aged pupils.
Sufferers struggle to grasp the relative value of numbers. If asked which is the larger of two playing cards showing five and eight, they would need to count all the symbols on each card.
However, research done by academics at London University's Institute of Education (IoE) shows that special teaching schemes and computer games can help improve pupils' abilities.
Professor Diana Laurillard from the IoE, a co-author of the new research with Professor Butterworth, said: "Just because dyscalculia is inherited does not mean that there is nothing that can be done about it.
"As with dyslexia, specialised teaching can help. We have developed software resources specifically to help children with dyscalculia."
The report calls for specialised teaching to be made available in more mainstream schools, but claims that school are unable to provide it because of the cost.
Jane Imrie, deputy director of the National Centre for Excellence in Teaching of Mathematics, said that with budgets under pressure schools can be reluctant to part with money to tackle the condition.
Mike Welsh, head of Goddard Park Primary in Swindon, employs a specialist teacher for children whose maths ability is assessed as being in the bottom 5 per cent.
He said: "People may have heard of the word dyscalculia, but what is missing is the early identification of children. I have met children at secondary school who have not been identified in medical terms until they are 13 or 14."
Sharon Bowden is vice-principal at Mark College in Highbridge, Somerset, a specialist residential secondary school for children with specific learning difficulties, including dyscalculia.
"We have children who arrive with no level of confidence at all in maths and most of them are able to take their GCSE and gain a pass grade," she said. "We don't label the children because it is the strategy that is important. If you work in a way that is practical, interactive and multi-sensory, that helps everybody, not just dyscalculics."
A spokesman for the Department for Education said: "Our green paper sets out how every child with SEN must get the help they need - including overhauling initial teacher training and staff's professional development so schools are better equipped to help raise the attainment of pupils."
Children with dyscalculia often use their fingers to do simple addition long after the age when most others stop.
To count down from 10, they will often count from one to 10, then one to nine and so on. Those with the condition also find it difficult to make approximate estimations and might calculate the height of a normal room as 200ft.
Source: Institute of Education.