Medium Sudoku

A step up without a change of technique

Medium puzzles are built with 35 to 39 givens, five or six fewer than Easy. The logic they need is exactly the same — the solver still finishes them using only naked and hidden singles — but the singles are further apart.

That gap is the entire difficulty. On Easy, the next move is usually next to your last one. On Medium you finish a box and then have to search the rest of the grid for where the chain continues.

When notes start paying off

You can finish every Medium puzzle without pencil marks, but this is the level where writing them starts to save time. Filling candidates into one stubborn row often reveals a hidden single you scanned past three times.

Use Notes as a tool for a single unit rather than filling the whole grid. Mark the row or box you are stuck on, take the move it hands you, and clear them.

A scanning order that works

• Finish every digit that has six or more copies on the board — those are nearly forced.
• Look at boxes with only two or three empty cells before looking at rows.
• After each placement, check the row, column and box it sits in before moving on.
• When nothing moves, pencil in one unit rather than restarting the scan.

The benchmark level

Medium is the level most players use to measure themselves, because it is hard enough to require attention and short enough to finish in one sitting. If you solve one without opening Notes, Hard is where the real eliminations begin.