The player receives an empty 9 by 9 square with 81 tiles. In each of the squares, you need to write a number from 1 to 9. The numbers should not be repeated in a row or column.
Additionally, the whole square is divided into separate blocks that can contain several cells. In the upper corner of one of the blocks, there is an icon of a mathematical operation: addition, subtraction, multiplication, and division. There is also a small number that shows the result of the action. The participant has to print the required number of numbers that, when added, subtracted or otherwise added, will give the number in the corner of the cell.
To keep track of the numbers, use the virtual layout below the playing field. The C key helps to delete the entered numbers.
If the player makes a mistake and there is already a number in the row, the square will be highlighted in red. Correct the mistake and print only the correct combinations.
You can print the game, get guesses, or switch to solving it from other gadgets using a QR code. After using a few digits, you can click on the check key and get the answer. If there are errors, the blocks with them will be highlighted in a different colour.
Simpler variants of the game are available. To do this, you need to select the parameters of the playing field in the settings: 3 by 3, 6 by 6, or 9 by 9 for real intellectuals.