This is a mind puzzle, that means you have to solve the puzzle in your mind without seeing directly how the single
pieces fit together. For every of the 9 pieces you have to input the right number. First you have to make a piece to the
active piece by mouse click or by using of the arrow keys. The number of the active piece is displayed with red colour.
Now press the appropriate number.
Here you have to change only one number from 0 to 9, then the game is solved.