Last November, Jill got herself screened for learning disabilities. She found that while her IQ is above average, her numerical ability is equivalent to that of an 11-year-old because she has something called dyscalculia. The diagnosis came partly as a relief, because it explained a lot of difficulties she had in her day-to-day life. She can't easily read a traditional, analogue clock, for example, and always arrives 20 minutes early for fear of being late. When it comes to paying in shops or restaurants, she hands her wallet to a friend and asks them to do the calculation, knowing that she is likely to get it wrong.

Welcome to the stressful world of dyscalculia, where numbers rule because inhabitants are continually trying to avoid situations in which they have to perform even basic calculations. Despite affecting about 5 per cent of people - roughly the same proportion as are dyslexic - dyscalculia has long been neglected by science, and people with it incorrectly labelled as stupid. Now, though, researchers are starting to get to the root of the problem, bringing hope that dyscalculic children will start to get specialist help just as youngsters with dyslexia do.