But the new study uses a different form of stimulation, known as transcranial random noise stimulation (TRNS), which applies randomly fluctuating currents (within certain parameters) to the head.
Six months later, when participants were contacted again and asked to solve calculations, researchers found that the group which had received five days of transcranial random noise stimulation showed "superior long-term performance, compared to sham controls".
But he said transcranial random noise stimulation could help more people because it had the potential to improve the ability to add, subtract or multiply a string of numbers in your head - not just new number learning.