Day 1 · September 2, 2026
Scan one area
Start with a row, column, or 3×3 box that is nearly full.
Name the missing digits, then check the crossing lines before placing one.
September 2–9, 2026
Seven days to solve with more confidence.
Learn one useful technique each day, then try the September 9 grid without a clue. Progress stays on this device.
September 9 is widely observed as International Sudoku Day, a date that echoes the classic 9 × 9 grid. Puzzle-source note
September 2–8 · Open Coach
The Coach is open to everyone.
On every grid you can already play, ask for as many clues or guided explanations as you need. The starting check and September 9 final stay without clues.
No account, payment card, or automatic renewal. Your plan does not change.Your local progress0 of 7 practice grids completeYour first move will be saved on this device.
Starting check · no clues
See where you are before the lessons.
Solve one verified grid without clues or Guided solve. Completion and corrected mistakes form the baseline; speed is not a score.
7 days, 7 techniques
Notice one piece of evidence, use it on a real grid, and return later. The lesson link explains the complete proof; the grid is the independent transfer.
Day 2 · September 3, 2026
Keep candidates accurate
Several digits may still fit in an empty cell. These possible digits are candidates.
Write only the digits allowed by the row, column, and 3×3 box; update them after every placement.
Day 3 · September 4, 2026
Find one remaining candidate
If every digit but one is ruled out for a cell, only one candidate remains.
Check all three areas around the cell, place that digit, then update nearby notes.
Day 4 · September 5, 2026
Find one remaining place
A digit may have several candidates in one cell but only one possible place in an area.
Follow one digit across the whole row, column, or 3×3 box and place it where no other cell can take it.
Day 5 · September 6, 2026
Use box–line interactions
In a 3×3 box, every candidate for one digit may lie on the same row or column.
That box reserves the digit on the shared line, so remove it from the rest of that line.
Day 6 · September 7, 2026
Reserve two digits
Two cells in one area may contain the same two candidates and no others.
Those two digits belong to those two cells, so remove both candidates from the area’s other cells.
Day 7 · September 8, 2026
Reveal a hidden pair
Two digits in one area may appear as candidates in the same two cells and nowhere else.
Keep those two digits in the pair cells and remove the cells’ other candidates.
September 9 · No Hint 9/9
Can you complete this grid without a clue?
The final grid is verified, rated hard, and uses the same rules and board controls as the learning week. Notes, pause, and resume are allowed.
Lessons
Explore the learning path →Want to make the final grid feel more familiar?
Open the learning path and practice the methods in a proof-first order.