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A puzzle that sounds as if it should have Japanese origins, Hidato was invented by an Israeli mathematician called Gyora Benedek. He explains:
It was a sunny day in Eilat, as always. I was scuba diving. Suddenly a huge school of small fish swam by...so fast that I could not follow them with my eyes. All I could see were spots along the route they passed, places where they made their sudden turns. They disappeared behind a coral reef to emerge again at an unexpected spot. It was dizzying and puzzling – maybe that was what made me think of a puzzle.
The connection between Benedek's brilliant invention (Hidato) and a shoal of fish is not immediately apparent.
The puzzle has appeared in some English newspapers, including The Daily Telegraph. It is popular in Japan.
In each puzzle, the smallest and greatest numbers are given. Other numbers are provided as clues. Each puzzle has a unique solution. Irregular grids are sometimes used.
Our example puzzle has been provided by Philipp Hübner.