Enter the numbers 1 to 9 as required into the grid, and press "solve" to try and solve it. Any input other than the digits 1 through 9 will be treated as that box being blank.

When you press solve, the computer will return as many boxes filled in as it can manage.

The boxes are coded as follows:

- 5 - This number was given to the computer.
- 5 - This number was filled in by the computer.
- 5 - This number is newly entered.

The checkbox makes the solver show the possibilities remaining for each unsolved square.