Millions of employees believe that their lack of basic skills has lost money for their companies and themselves, according to a survey.
Young people rely on the help of a computer spell-checker
A survey for Learndirect, the adult training agency, highlights the extent of weaknesses in English and maths.
Based on a sample of 1,000 people, the survey projected that 14.6m workers had lost their firms money because of literacy and numeracy mistakes.
It also suggested two-thirds of people relied on computer spell-checkers.
The Learndirect survey examined how a lack of basic skills affects working and home lives - and found widespread anxieties.
Spelling, currency exchange, comparing price tariffs, measuring volume and helping children with homework are among the areas where literacy and numeracy are causing problems and embarrassment.
Almost two in five of the people surveyed said that they relied on someone else at work to check their calculations.
A television campaign urged people to shake off their learning gremlins
There was also a widespread dependence on computer spell-checkers, particularly among the young. The survey suggested that 67% of people relied on spell-checkers - with this rising to 75% among 16 to 30-year-olds.
The survey calculated that people were losing more than £800m of their own money each year as a result of their mistakes with numbers.
And based on this sample, the survey projected that 1.4 million people believed they had missed promotion because of weaknesses with literacy and numeracy.
Skills Minister Phil Hope says that, since 2001, more than 1.5 million people have "beaten their gremlins" by getting a basic skills qualification, under the Skills for Life strategy.
This provides free tuition for adults who have skills below GCSE level - with national Skills for Life qualifications in language, literacy and numeracy.
"Improving your skills can help you earn more and will enable you to progress to further learning, as well as making you more confident and more able at home," said Mr Hope.
A government-commissioned report into skills, published by Lord Leitch in December, called for a radical overhaul in adult training - and warned that the UK's skill base was lower than many international competitors.
The report said that five million adults lacked functional literacy and more than 17 million had difficulties with numbers.
More than one in six youngsters left school unable to read, write or add up properly, said the report.