What changes on Medium?
Medium Circle Sudoku drops several starter numbers from the Easy version. That means you can’t just skim the ring for an obvious gap — you’ll need to check the sector AND the arc box before most moves.
If Medium feels like a big jump, take a break and warm up with a couple of Easy puzzles first. The Circle Sudoku page has the full rules and worked examples.
Three circle-specific tricks
-
Sector scan
Pick a sector with four or five givens. The missing digits can only go in the empty cells. Check each empty cell against its ring and arc box — usually only one legal spot remains.
-
Arc-box cross-check
An arc box spans two sectors and three rings. Any digit that appears in the surrounding rings/sectors is eliminated from the whole arc box. Finding a single empty cell in an arc box that can only hold one digit is a huge win.
-
Ring-21 check
The six digits in any ring always sum to 21. If five cells add to 18, the last must be 3. Handy for those last-few-cells finishes!
When you get stuck
- ✏️ Turn on Auto Notes for a clean candidate-map view
- 🔎 Tap Check — if you have a wrong digit, fix it before going further
- 💡 Tap Hint to fill one cell (it counts in stats, but that’s fine)
- ↻ Tap Undo to step back if a placement turned out wrong
Ready for the next step?
When Medium Circle Sudoku takes you under 6 minutes, try Hard Circle Sudoku. Hard puzzles have fewer clues and need a couple more strategies.
Frequently asked questions
How long should Medium Circle Sudoku take?
Most kids finish a Medium puzzle in 6 to 12 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.
Why are there fewer given numbers?
Fewer starting digits force you to use the arc-box rule more. Circle Sudoku’s three overlapping groups still give plenty of clues, just not as obvious ones.
Is there a keyboard shortcut for notes?
Yes — press P (for Pencil) on any keyboard to toggle Notes mode. Then type the digits 1–6 to jot candidates.
Try other sudoku games
Different rules, same friendly board. Pick a sibling puzzle to play next.