Medium Sudoku: A Free Medium Sudoku Every Day

What makes a medium sudoku harder

With 49 empty squares instead of 41, a medium sudoku has stretches where no box offers an obvious spot for any digit. That is where the real solving starts. Medium is the level most daily players settle into: challenging enough to need focus, short enough to finish in 10 to 20 minutes.

Techniques for medium boards

Naked singles

Pick an empty square and list the digits already used in its row, column and box. When eight digits are taken, the ninth is the answer. Medium boards are full of these once you start checking squares rather than digits.

Hidden singles

Turn it around: pick a box and a digit missing from it. If that digit can go in only one of the box's empty squares, place it, even if that square has other candidates too. Do the same for rows and columns.

Light pencil marks

You do not need notes for every square, but in a crowded corner it helps to write down the two or three possible digits for each empty square on a scrap of paper. When one of them gets settled, the others often fall in a chain.

A routine that works

1. Scan all nine digits once, as on an easy board.
2. Fill every row, column and box that is down to one or two empty squares.
3. Check the squares in the busiest areas for naked singles.
4. Look for hidden singles box by box.
5. If you are still stuck, note candidates for one box and its neighbors.

Medium boards rarely need anything beyond these steps. If you catch yourself guessing, step back: there is a logical move you have not spotted yet.

Next steps

Comfortable here? The hard sudoku starts with only 26 givens and rewards pairs, pointing and full candidate notes. Want a lighter day? Go back to the easy sudoku or play today's crossword. All levels and the kids' boards are on the main sudoku page.