Imagine you run a bakery. One day you ask your workers to prepare 4,500 loaves instead of the usual 5,000. You go away, secure in the knowledge that your request will be acted on.
It is. The staff bake the normal 5,000 loaves and then throw 500 away.
Judith Swift, the TUC's national development worker for basic skills, tells this true story to illustrate how important good maths skills are for employees - and employers.
Numeracy is "massive" at work, she says. There are three key areas: pay and pensions, health and safety, and productivity and wastage.
Consider, for example, the employee who confessed to her union learning representative that she could not count in units of 10. Once the problem was out in the open, it was easily fixed and the company no longer got complaints about boxes containing 20 or 40 units when 30 were ordered.
Judith Swift works for the TUC's Learning Services which advises union learning reps on how to help employees access vital training. There are now 6,500 reps and since 1998 they have supported 36,000 workers through the pound;40 million Union Learning Fund set up by the Government.
Many of those 36,000 employees had fundamental and easily identifiable numeracy needs, says Judith. Take safety at work. Two years ago the TUC and the Health and Safety Executive were shocked to discover that nearly half of COSHH (control of substances hazardous to health) sheets were incorrectly filled out. The management of dangerous substances as well as risk assessment, noise levels, and computer screen regulations often come down to pure numbers, she says. If you don't understand ratios, you cannot mix up chemicals for swimming pools. Even a diagram showing what weights it is safe to lift can be confusing for people who do not understand how the data is represented.
The growth of the union learning rep scheme has given many workers the confidence to admit their problems. Reps are accustomed to being asked to check pay slips. Aside from the nightmare of pensions, many low-paid workers have tortuous bonus systems which they need help understanding.
"Run courses on pay and pensions, map them across to the numeracy curriculum and you get people thinking about their numeracy needs," says Judith. Such needs are being tackled in the health service too, through its new "corporate" university.
The importance of numeracy to medical staff was underlined when the National Patient Safety Agency told the recent Smith inquiry on maths of 32 dosage errors, 12 of which were fatal. In one case, a premature baby was given 100 times too much morphine.
But safety is not the only issue for patients. According to Bob Fryer, chief executive of the NHS University: "Actually understanding the meaning and implications of numbers allows people to manage their own lives and not be dependent on others to know about the numbers of this or that, or the combinations of treatments. It becomes a matter of dignity."