My book 50 Mathematical Puzzles consists of puzzles selected from Szczepan Jeleński’s book Lilavati written in 1926. In this project, I attempted to create a new formula for a children’s book with puzzles. I obtained very clear separation of puzzles and answers by reversing them in relation to each other, and placing them in different areas of the book. This invites the reader into a game: a continuation of the puzzle has to be found. Each double-page was designed individually, while still allowing a permanent place for the page header. I introduced freehand drawings to ease the impression of mathematical purity (a strong contrast between black and white, and consistent use of two typefaces).