The rules in one minute
Fill the empty cells with the numbers 1 to 9. Each row, each column and each outlined 3 by 3 box must contain every number once. The given numbers stay in place. You do not need arithmetic; a number represents its place in the pattern. Start with a row or box that already contains several givens.
Keep the answer for later
The PDF has the puzzle on the first page and the completed grid on the second. Print just page 1 for solving. Use the displayed seed to make the same grid again with this version of the generator. Large print changes the spacing and number size without changing the answer.
Choose a technique level
Easy solves with naked singles. Moderate also needs hidden singles. Challenging needs locked candidates or naked pairs beyond singles. Every category must complete without guessing and pass an exactly-one-solution check. The clue count is not the grade. Choose a level and Generate from seed to apply it; see our difficulty guide for the full versioned rule.