Yohaku

Yohaku is a math logic puzzle in the same vein as kakuro, another variation of sudoku that actually uses math. It was developed by a math teacher from Canada to help his students. The puzzle allows addition and multiplication to fill in a grid with the results for each row and column already displayed. You can use numbers or algebraic expressions in the grid. There can also be constraints added to the puzzle to make it harder or easier to solve. It turns out you can create these puzzles by essentially reverse engineering them – filling in the squares of the grid and calculating each result, and then publishing the puzzle with the results and blanking out the inputs. You can add constraints for the user to use that match the numbers you input in the generator. The first screen you'll see here is the generator – fill in the white squares by putting the cursor in them and typing; the results will be calculated by the app. You can then add constraints and generate the puzzle, which is a downloadable HTML file that you can distribute to friends. Entries in the squares can be positive or negative, whole numbers or fractions for now. Plans are to add algebraic expressions and other kinds of numbers later.

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