Medium printable sudoku
Thirty clues, and the solve turns on naked pairs, hidden pairs and a pointing pair or two. The first setting where pencil marks earn their keep.
What changes at medium
Thirty clues instead of forty-two, and the solve stops being a scan. You will place most digits with singles, as before, but somewhere in the middle the board stalls and the move that unsticks it is a naked pair, a hidden pair, or a pointing pair.
On the 600 boards this setting produced, the technique that topped out the solve was:
| Technique | Boards out of 600 |
|---|---|
| Naked pair | 477 |
| Hidden pair | 64 |
| Pointing pair | 48 |
| Something even cheaper | 8 |
| Claiming / naked triple | 3 |
Naked pair is the workhorse by a wide margin. If you learn one technique to move up from easy, learn that one — it is the answer to four boards in five at this level.
The eight honest exceptions
Eight of the 600 boards were rated medium but turned out to need nothing beyond singles. That is not a bug being confessed; it is what happens when a generator digs to a clue count and the clue placement happens to fall kindly. We could filter them out, but the filter would have to relax something else to keep the sheet full, and a sheet that quietly changes its own rule is worse than a sheet with an easy puzzle on it.
If one puzzle feels too gentle, skip it. The next one probably will not.
Pencil marks start to matter here
This is the first setting where candidate marks are worth printing. A naked pair is invisible without them: you are looking for two cells in one unit that hold the same two candidates, and you cannot compare lists you have not written down.
Print one sheet with marks on and work it that way. Once pairs feel routine, print another without, and see whether you can hold the two lists in your head. That progression — marks, then no marks — is the actual skill being trained.
Where medium sits in the ladder
It is the last setting that a patient scanner can finish without learning a named pattern. Everything above it — hard, expert, evil — requires a fish, a wing, or a chain. If you want to stay at medium for a while, that is a reasonable place to live; plenty of people play there for years.
When you are ready to move, the naked pair guide and the pointing guide are the two articles this sheet is built on, and there is a naked pair practice sheet that drills the first of them on its own.