7 min read · Updated April 2026
Numbly is Wordlio's daily Sudoku — a fresh 9×9 grid every day, same rules as classic Sudoku: fill every row, column, and 3×3 box with the digits 1 through 9, no repeats. If you have ever stared at a half-solved grid and felt completely stuck, the problem is almost always that you are missing a technique. Here are the five that will get you through any Numbly puzzle.
Top Sudoku solvers write candidate numbers (small pencil marks) in empty cells — all the digits that could possibly go there based on current eliminations. Digital Sudoku tools let you toggle candidate mode. If Numbly supports it, use it. If not, keep a rough mental note of 2–3 candidate digits in the cells you are working on. All five techniques below are easier with candidates visible.
A naked single is a cell that can only contain one digit — every other digit 1–9 already appears in its row, column, or box. This is the most common technique and where you should always start. Scan every empty cell and look for the ones with only one possible value. Fill those first. Often solving one naked single reveals another, creating a chain of easy fills.
A hidden single is a digit that can only go in one cell within a row, column, or box — even though that cell might appear to have multiple candidates. For example: if the number 7 can only fit in one cell within a given 3×3 box (all other cells in that box already have 7 in their row or column), then 7 must go there. Scan each box, row, and column for digits that have only one valid home.
When two cells in the same row, column, or box each have exactly the same two candidates — say both show {4, 7} — those two digits must occupy those two cells (in some order). This means you can eliminate 4 and 7 from every other cell in that shared row, column, or box. This often unlocks hidden singles elsewhere. Look for matching pairs of candidates anywhere on the board.
When all possible positions for a digit within a 3×3 box are confined to a single row or column, that digit can be eliminated from all other cells in that row or column outside the box. For example: if 3 can only go in cells at row 2, columns 4–5 within one box, then 3 cannot appear in row 2 in any other box. This shrinks candidates elsewhere and often triggers naked or hidden singles.
X-Wing is the most powerful technique on this list and the one that solves puzzles that seem completely locked. Find a digit that appears as a candidate in exactly two cells in each of two different rows, and those cells occupy the same two columns. That digit can then be eliminated from all other cells in those two columns. The pattern forms an "X" shape across the grid — hence the name. X-Wings are rare in beginner puzzles but appear in medium and hard Numbly grids.
Always work from simplest to most complex:
Most Numbly grids at normal difficulty can be solved with techniques 1 and 2 alone. Harder grids add 3 and 4. If you ever feel you need to guess, apply technique 5 before giving in — there is almost certainly a logical path.
If you want to get through Numbly quickly, focus your attention on the boxes, rows, and columns that are already most filled in. A row with 7 of 9 digits filled is trivial — the remaining two cells are nearly solved. Starting with the densest areas gives you fast wins that propagate elsewhere.
Today's Numbly is live. Open it and try technique 1 first.
Play Today's Numbly →See also: Numbly: Your Daily Sudoku Guide