Millions of people are struggling to understand their payslips or calculate money in shops, campaigners have said, as they warned the UK's attitude to maths must change.
Being bad at maths should no longer be seen as a "badge of honour" or down to genetics, according to National Numeracy, a new organisation which aims to challenge the nation's entrenched negative view of the subject.
Chris Humphries, chairman of the group, said that poor numeracy skills can "blight" an individual's life, leaving them at a higher risk of being excluded from school, or out of work as an adult.
Figures from a Government survey, published last year, show that 17 million adults in England have basic maths skills that are, at best, the same as an 11-year-old, he said.
The Skills for Life survey, which questioned 7,000 16 to 65-year-olds, showed that almost half of the working age population has numeracy skills roughly the same as those expected of primary school children, and the proportion has risen (from 47% to 49%) in the last eight years.
Speaking at the launch of National Numeracy, Mr Humphries, former chief executive of the UK Commission for Employment and Skills, said: "That's a scary figure, because what it means is they often can't understand deductions on their payslip, they often can't calculate or give change.
"They have problems with timetables, they are certainly going to have problems with tax and even with interpreting graphs, charts and metres that are necessary for their jobs. It does matter, poor numeracy seriously blights an individual's life chances."
Mike Ellicock, chief executive of National Numeracy, said: "We want to challenge this 'I can't do maths' attitude that is prevalent in the UK", adding that it was vital that all primary school teachers understand key maths concepts, as young children who fail to learn the basics will suffer later on.
"For my money Key Stage 1 (five to seven-year-olds) is the crucial area, so there has been talk about having specialist maths teachers in Years 5 and 6, but my view is Key Stage 1 is crucial, and if you look at children and young adults that struggle with maths later in their lives you can pretty quickly trace it back to the ideas that they met in Key Stage 1."
A YouGov poll of 2,068 adults, commissioned by National Numeracy, reveals that while four in five (80%) would feel embarrassed to tell someone they were bad at reading and writing, just more than half (56%) would feel embarrassed about saying the same of their maths skills.