When asked to perform similar tasks with a paper and pencil they "performed worse than without using paper and pencil ".
It is conceivable to be better at mental count and the reason can be that those children’s daily lives are based on these calculations in their heads, practice helps, but when it comes to writing down the mathematics there are many hurdles for such kids like unfamiliarity with the concept of solving on paper and in some cases dyslexia etc.
