Primary children's maths scores have shown little improvement despite the Pounds 2.3 billion spent each year on the subject, a National Audit Office report shows.
This year, 78 per cent of 11-year-olds reached the expected level 4 in maths - a rise of just six percentage points since 2000 - while spending on primary education has risen by 30 per cent over the same period.
The Houses of Parliament's audit watchdog warned that many children - of all abilities - were not reaching their potential.
It found that the proportion of pupils who improved by two full levels in maths had been between 74 and 76 per cent for the past five years, and warned that achieving the Government's targets of 84.5 per cent of children progressing two levels by 2011 would be a "considerable challenge".
Edward Leigh, chairman of the House of Commons public accounts committee, said: "The bottom line is that improvements in mathematics results since 2000 have been unimpressive."
The gap between children from disadvantaged backgrounds and their peers had narrowed only slightly over the past three years. Girls were also at risk of being left behind, with boys making better progress in junior school.
The research team said that one reason for the slow down was the relative difficulty of improving the maths skills of the less able pupils who were being left behind.
But the team said more progress could be made with the money available, in particular the training of teachers in assessment of pupils could be "considerably improved".
They said that 66,000 pupils who had done well at age seven failed to realise that potential at 11 - a finding that echoed Sir Peter Williams' review of early maths teaching, which was published this year and called for more and better subject training for teachers.
The team found that the biggest factor in whether pupils went to secondary school enjoying maths was whether they had been taught the subject by an enthusiastic teacher at primary level.
They estimated that Pounds 3 million of the Pounds 80m spent on the national strategies last year went towards primary maths.
While the Primary National Strategy - the Government's main scheme to improve primary maths - could be credited with improving consistency in planning and teaching, there were weaknesses in assessing pupils and the use and application of maths, they said.
The revised framework, introduced in September last year, addressed these areas. The National Audit Office said it was too early to assess whether this was working, but it found that one in four teachers thought the revised framework had made little or no impact on raising attainment so far.
The watchdog also found that maths resources were skewed towards test preparation in Year 6.
Angela Hands, who directed the research, said there was no clear answer to whether the money the Government was spending on primary maths was worth it.
"You need to spend a certain amount in order to sustain that big improvement that has happened," she said. "There has been a continuous improvement at key stage 2, but there are things that are not happening - which we think could be - with the money that is there, such as better training of teachers in assessment of pupils, and better management of data by schools, so they identify underachieving children."
The Government has agreed to spend Pounds 24m over the next three years on setting up a training scheme for 13,000 primary teachers. It is also running pilots of the Every Child Counts programme, which targets the lowest achieving pupils.
Since 1999-2000, there has been a real terms increase in expenditure on primary schools of more than 30 per cent.
Pounds 2.3 billion was spent on teaching maths in primaries in 2006-2007.
Since 2000, maths attainment at key stage 1 has levelled off and there have been small improvements at key stage 2.
But 66,000 pupils who achieved well aged seven failed to make the progress expected by age 11.
Girls' progress in maths between the ages of seven and 11 is lower than boys', and particularly marked for those who are less able at maths.
A good and encouraging teacher was the most common reason that secondary pupils gave for enjoying maths in primary school.
Teachers need more subject-based training in maths and help with pupil assessment.
More needs to be done to increase pupils' enjoyment of maths.
Source: National Audit Office, `Mathematics Performance in Primary Schools: Getting the Best Results'
The National Audit Office has come up with a lot of numbers about maths in primary schools, but no neat solution.
The watchdog concludes that the expenditure has helped to improve results, but not as much as hoped. This is partly because it was being spent on the wrong things - an overly complicated website, for example - but also because it is a difficult problem to solve.
Picking up early on children who do not understand maths is not as simple as it may seem. Quiet girls are particularly at risk of being left behind, starting off well using basic but inefficient methods, such as counting on, which work until they are asked to add 672 to 540 and have to spend playtime counting up.
Why would anyone want to do that? It would be like having learnt how sounds and letters are connected, then instead of reading fluently being condemned to continue "robot reading" by s-ou-n-d-ing ou-t ev-e-ry w-o- rd.
The solution should be obvious. You learn a more efficient way - and you learn it because you want to do maths.
The watchdog makes five recommendations: keep a closer eye on progress; help girls; improve the Primary National Strategy website; provide more subject training for teachers; and do more to increase pupils' enjoyment of maths.
It cites ideas from other countries, such as the KidzKount website in The Netherlands, which pupils access mainly at home to play maths-based games. In 2007, the site was accessed more than 22 million times.
The country also holds a Big Arithmetic Day, open to all primaries. Those taking part suspend normal lessons and pupils work on a project - on the concept of time, for example - and create something to take home to their parents.
One of the most intractable problems in the UK is the national attitude that maths is boring. But maths is not inherently more boring than any other subject, as any fan of the television series Numberjacks will tell you.
And, for children, the most important factor in whether they find maths enjoyable is whether they have an enthusiastic teacher. That should be pretty simple, eh?
Helen Ward, TES primary specialist.