What changes on Medium?
Medium X-Sudoku drops about a quarter of the starter numbers you saw on Easy. That means more of the puzzle is solved from the diagonals, not from the obvious row/column clues. Don’t panic — every Medium puzzle on this site still has exactly one solution, and you can always find it without guessing.
If Medium feels like a big jump from Easy, that’s normal. Most kids spend a couple of weeks at Easy before Medium X starts to feel comfortable. For a refresher on the basics, the X-Sudoku page has the full rules with worked examples.
Three diagonal tricks to try
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Diagonal scan
After every placement, glance at both big diagonals. If a diagonal has five or six digits, you can often eliminate a lot of candidates on the remaining cells straight away.
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The centre is king
The centre cell of the grid (row 5, column 5) sits on both diagonals. It’s constrained by row, column, box AND both diagonals — so it often solves first, and it unlocks cells on both diagonals at once.
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Diagonal 45
Each diagonal has nine cells and must total 45. If eight cells are filled and add to 38, the last cell must be 7. A surprisingly useful check when you’re almost done.
How to spot a forced digit
A "forced digit" is when only one number can go in a cell, no matter how you look at it. Spotting them is the main skill on Medium. Here’s the order we recommend: check the row, check the column, check the 3×3 box, then check the diagonal (if the cell is on one). If that leaves only one legal number, write it in.
Sometimes the row and column leave 3 or 4 options, but the diagonal knocks out all but one. This is the pay-off for learning X-Sudoku — the diagonals do real work, not just decoration.
On cells that aren’t on a diagonal, solving feels exactly like classic sudoku. On diagonal cells, always remember to include that fourth check.
When you get stuck
- ✏️ Turn on Auto Notes — on X-Sudoku this is doubly useful
- 🔎 Tap Check to make sure every filled cell is still correct
- 💡 Tap Hint to fill one cell (it counts in your stats, but it’s okay!)
- ↻ Tap Undo to go back if a guess turned out wrong
Ready for the next step?
When Medium X-Sudoku puzzles take you under 10 minutes, give Hard X-Sudoku a try. Hard puzzles have way fewer givens and you’ll need every trick from this page plus a few more.
Frequently asked questions
How long should Medium X-Sudoku take?
Most kids finish a Medium puzzle in 10 to 18 minutes. If it takes longer, that’s fine — use Notes and tap Check whenever you want to make sure you’re on track.
Can I switch back to Easy?
Of course — just tap the Easy tab at the top of the board. Your Medium puzzle saves automatically.
Are there fewer starter numbers than classic Medium sudoku?
Yes, just a little. Because the two diagonals give extra clues, we can remove a few more givens and keep the same difficulty feel.
Should I memorise anything?
Not really. Just get used to always checking the diagonals when your selected cell sits on one. A lot of kids find that becomes a habit after three or four puzzles.
Try other sudoku games
Different rules, same friendly board. Pick a sibling puzzle to play next.