By zapping brains in maths lessons, scientists claim to have boosted students' abilities by a third.
Participants became quicker at calculating and learned up to five times faster, they said.
The Oxford University team gave maths training to 51 students.
Around half of them had a light electrical current passed through their brains as they learned.
After five sessions, those who used the treatment learned new sums and recalled figures, such as times tables, much better than those who did not.
They also calculated 30 per cent faster - and the skill gap remained in tests six months later.
Lead researcher Dr Roi Cohen Kadosh, of Oxford University's department of experimental psychology, said he hoped to help people who are bad at maths.
"The study suggests a safe and cheap way we can improve people's maths with limited intervention," he said.
"We are stimulating the part of the brain that deals with maths, because low numeracy is a problem for many people."
The treatment is painless and non-invasive, he added.
An estimated one in five of us struggles with basic arithmetic, while one in 15 suffers from dyscalculia, which can make tasks such as counting change impossible.
It is unclear how the electrical stimulation works, but brain scans suggest it increases the brain's supply of oxygen and nutrients.
The research, published in journal Current Biology, involved five 45 minute maths sessions, with 25 of the participants given brain stimulation for 20 minutes.
- DAILY MAIL