Pedro Dao dos Santos is the youngest of 13 children. He lives in a small town in the interior of Brazil. Every day the 10-year-old hangs out at the local petrol station trying to earn a little money for his family.
He polishes shoes and sells homemade lollipops to reluctant passers by. Most ignore the scruffy child and refuse to buy his wares. But every now and then, Pedro throws a gauntlet down to his prospective customers.
"Go on, ask me any sum you like," he says. "If I don't do it within two minutes I'll polish your shoes for free."
The strangers always lose the bet because Pedro is a mathematics genius who can work out seven digit cubic roots in his head.
Thousands of brainy children living in Brazil's slums are wasting their intellect - despite achieving significantly higher than normal grades for their age and background.
Pedro first came to notice when a statistics professor happened to be passing through the small town where he lives.
"He asked me what the cubic root of 1,5625 was: so I told him it was 25," explains the boy. "Then he asked me the square root of 5,6169 and I said 237. I think he was surprised."
Pedro, who attends a poorly funded local school, says he does the calculations on the "walls of his head". He admits that even his maths teacher has difficulty keeping up with him. "None of my family likes numbers the way I do," he says. "My mother says it's a gift from God and tells me to use my brain to get out of the slum.
"If I have a chance to go to college I'd like to become an engineer. But the problem is that I need to work because my family are very poor."
Maria Clara Salgado de Gama is the technical director of the Maria Telles Social Institute that helps gifted children from deprived families.
"The percentage of very bright children living in the slum is exactly the same as those from middle class families," she says.
"What these children lack is a general knowledge but they often display a talent for mathematics or painting, for example, that far exceeds their basic education."
Gama, whose project helps brainy kids in Rio's slums, works with a team of education specialists who measure the intellect of the children using logic tests similar to the MENSA scheme.
Out of 200 children tested so far, six have been selected to go a special after-school class where experts help develop the child's particular intellectual attribute.
Currently only nine of Brazil's 27 states have similar projects to help gifted children from the slums. Marsyl Mettra, President of the Brazilian Association for Gifted Children, believes that the vast majority of poor but bright children are going to waste because local authorities provide no extra facilities to help them.
"When a child is poor they go to bad schools with teachers who don't know how to develop their potential," she says.
"Their parents don't understand them and this leads to frustration and boredom for the child. This will only change if people recognise that the poor can also be intelligent."
For now though, Pedro uses his grey matter to entertain customers. "My school doesn't have the facilities to help me," he says. "This makes me very sad because all I want to do is learn."
