The country is about to suffer the full consequences of a recession that began with very poor calculations of the price of risk. So it is not just children who need the ability to interpret statistical data (see page 14). A poor appreciation of probability lies behind needless medical scares, false hope in the lottery and most apparently amazing coincidences. People also tend to respond excessively to present dangers, even if they are small. That impulse is why we react to train crashes by closing lines and forcing passengers on to the roads with a large net increase in risk. It would help if we taught children to work out the basic risks they are running.

But it seems there is a very long way to go. According to the official figures, 6 per cent of 11-year-olds in England left primary school every year no more numerate than the average seven or eight-year-old. Almost seven million adults perform below the level expected of a nine-year-old in mathematics. Not surprisingly, innumerate adults struggle to find work. They end up with worse health problems and more likely to be in trouble with the police. Add the cost of healthcare and crime to the tax revenue forgone, the benefit costs and the extra educational provision, and the total bill for innumeracy comes, according to KPMG, to £2.4 billion.

Companies are now being requested to sign up as sponsors, to allow more children the benefit of extra teaching. This is surely one for the bankers. They claimed that managing risk cleverly was their speciality. Now that they have been unmasked, it might be time they took some extra tuition themselves. But if that is too much to hope for, they might at least pay for others to do so.