Sangaku

Sangaku is a kind of puzzle that people in Japan used to solve a long time ago. Think of it like a game or a brain teaser that makes you think really hard. The puzzle is usually drawn on a wooden board or a piece of paper and it looks like a picture with lines, numbers, and shapes.

Sometimes, the puzzle is about finding the area of a shape or the length of a line. Other times, it might be about figuring out how to fit different shapes together, like a puzzle.

People in Japan used to solve these puzzles as a way to practice their math skills and also to have fun. Some of the puzzles were really hard, but when someone finally figured it out, they would feel really proud of themselves.

Nowadays, people still solve sangaku puzzles as a way to train their brains and challenge themselves. It's like playing a game that makes you smarter!