Points
0 / 405
Mistakes0
Hints0
Paused
Crafting your puzzle…
Verified unique solution. Always.
Paused
Crafting your puzzle…
Verified unique solution. Always.
Every puzzle is generated fresh with a verified unique solution. Unlimited plays.
Copy Result places a one-line summary of your solve on the clipboard, ready to paste anywhere. The buttons above open a ready-made post.
A session analysis from your play, mapped to the six Real World IQ brain regions. Scroll to read it all — your Lifetime Cognitive Record grows with every solve.
Region values are session estimates from this puzzle's play pattern. Membership will extend this report with lifetime region trends, world percentiles, and printable certificates.
The remaining cells will be filled in for you and will score no points. Your puzzle will end as a revealed solve.
Fill the 9x9 grid so that every row, every column, and every 3x3 box contains the digits 1 through 9 exactly once. The puzzle starts with some numbers already placed — the givens. There is exactly one way to complete the grid, and every Parker Sudoku is machine-verified to guarantee it.
Scan a row, column, or box that is nearly full and ask: which digits are missing, and where can each one legally go? When only one cell can take a digit — or a cell can take only one digit — place it. That single idea solves every Easy puzzle in the book.
When you cannot place a digit with certainty, switch on Notes and pencil the possibilities into the corner of each cell. Strong solvers work the notes, not the grid.
Live mistake checking is exclusive to Easy. On Easy, a wrong entry turns red and the mistake counter ticks — a learning aid while you build your technique. From Medium upward, the board passes no judgment: your deductions stand on your own logic until the grid is complete. That is how real solvers — and real tournaments — play.
Unlimited puzzles, unlimited mistakes — nothing locks you out. Hints are always available and always explain the reasoning, so every hint makes you stronger. Cells filled by hints simply score no points.
Tap a cell to select it, then tap a number on the pad. Tap the same number again to erase it. The pad shows how many of each digit remain. Notes toggles pencil-mark mode; Auto Notes fills every legal candidate for you.
| 1–9 | Place digit |
| Shift + 1–9 | Pencil note |
| Arrow keys | Move around the board |
| Backspace / 0 | Erase cell |
| N | Toggle notes mode |
| U | Undo |
| H | Smart hint |
| P | Pause |
Every digit is worth its face value: place a 5, score 5 points. A completed grid always contains 405 points (each row's digits sum to 45, across nine rows). The starting numbers' share is already banked by the puzzle — your meter counts only the points left for you to solve. An easy board with 170 points given shows your target as 235: every one of those points is yours to earn.
Each difficulty multiplies every point:
| Easy | x1 — 405 total points |
| Medium | x2 — 810 total points |
| Hard | x3 — 1,215 total points |
| Grand Master | x5 — 2,025 total points |
Your meter follows the board: every number you place adds its face value the instant you enter it, and comes back off if you erase or change the cell. The score never reveals whether an entry is right or wrong — and the puzzle only completes when the grid is perfect, so only a true solve banks the total. Cells revealed by hints or Solve score zero — fair is fair.
Finish a puzzle and you receive a Real World IQ score: your earned-points performance (0–100, with a small penalty per mistake) multiplied by 2.0, plus a speed bonus of up to 20 points for beating the par time. A flawless, fast solve scores the maximum 220.
A cell where eight digits are already blocked by its row, column, and box. Only one candidate remains — place it. The bread and butter of every solve.
A digit that fits in only one cell of a row, column, or box — even though that cell has other candidates. Scan each digit 1–9 across each unit and ask: where can this digit live? If the answer is one place, it lives there.
When all of a digit's possible spots inside a box fall on a single row (or column), that digit must be in that box on that line — so erase it from the rest of the line. The reverse works too: a digit confined to one box within a row can be erased from the rest of that box. Your first true elimination weapon.
Two cells in one unit that share exactly the same two candidates. Those two digits are locked into those two cells, so remove them from every other cell of the unit. Triples work identically with three cells and three digits.
Two digits that fit only in the same two cells of a unit. Whatever else those cells were considering is noise — clear their other notes. Spotting hidden pairs early can crack a Medium wide open.
One digit, two rows, and in each row only two possible columns — the same two columns. The four cells form a rectangle, and the digit must occupy opposite corners. Erase that digit from those two columns everywhere else. Works equally with columns first.
Three two-candidate cells: a pivot holding XY sees two wings holding XZ and YZ. Whichever value the pivot takes, one wing becomes Z — so any cell that sees both wings can never be Z. The gateway to advanced solving.
Beyond these techniques live forcing chains, coloring, and trial trees — puzzles where you must follow a candidate's consequences several steps deep to find a contradiction. Our Grand Master tier is certified to require exactly this. Use notes religiously, work bivalue cells, and trust the chain. The Smart Hint will walk you through any position, and it always tells you why.