Pi Greco is an experimental prototype realized during the game jam Code4Play: a one day hackathon where designers, developers and makers worked together to hack old toys giving them new life, focusing on toys for children and learning in the internet of things.We decided to realize an interactive toy to teach math to children using one arduino uno, one raspberry, some resistence for the blocks, and for sure, old toys pieces. The interactive process is very simple and based on the metaphor of building blocks: if usually children play with blocks creating fantasy composition, with Pi Greco they use the blocks composing simple math operations. Shaking the base, Pi Greco asks to child to compose the right operation to obtain a specific number. Then the children can play with the blocks, trying to compose the right sequence of numbers and operators to obtain the request number. Every interaction is enriched with sounds to provide feedback.