Sudoku tips for beginners: your first 10 puzzles
Sudoku looks like a math puzzle but it isn’t you’ll never add, multiply, or do anything beyond placing the digits 1 through 9. The hard part is seeing which digit goes where. Here’s how to actually start if you’ve never finished a puzzle.
The rules in 60 seconds
A sudoku grid is 9×9. It’s also divided into nine 3×3 boxes (the bold-bordered squares you see grouping cells into thirds in each direction). Some cells start filled in; those are givens, you can’t change them.
Your job is to fill every empty cell with a digit 1-9 such that:
- Every row contains each digit exactly once.
- Every column contains each digit exactly once.
- Every 3×3 box contains each digit exactly once.
That’s it. No arithmetic. There’s always exactly one valid solution for a well-formed puzzle (Melio’s are all uniquely solvable, guaranteed). Solving it is about deduction, not guessing.
Start with the digit that appears the most
Look at the givens. Whichever digit shows up the most times, say there are six 5s already on the board, is your starting point. You only need three more to complete the digit, and the constraints from the existing six make each new placement easier to spot.
For each row, column, or box that’s missing your chosen digit, check whether you can deduce where it goes. Often you can: a 3×3 box without a 5 might only have one cell where a 5 is allowed (the other empty cells share a row or column with an existing 5, so they’re ruled out).
This technique has a name, cross-hatching and it’s how you’ll solve roughly 80% of easy puzzles without any other technique.
Hunt for “naked singles”
A naked single is a cell where only one digit can possibly go. Look at any empty cell: which digits are already in its row? Its column? Its 3×3 box? Cross them off. If only one digit is left, it has to go there.
On Melio Sudoku, the easier difficulties are full of naked singles waiting to be found. After cross-hatching for the most-common digit, scan the rest of the board for any cell where the rules force a single answer.
Use pencil marks the moment you’re stuck
Pencil marks (also called “notes”) are tiny candidate digits you write in a cell. On Melio Sudoku, tap the pencil-mark mode and then tap a cell + a number to add that number as a candidate.
The rule: in any empty cell, write down every digit that couldgo there (i.e., isn’t already in the cell’s row, column, or box). Now you can see your options laid out visually instead of having to recompute them every time you look at the cell.
Pencil marks turn an “I’m stuck” moment into “oh, there’s only one cell in this row that can be a 7.”
Hidden singles, the next-level scan
Once your pencil marks are in, look at any row, column, or box. Pick a digit, and check: how many cells in this unit can hold this digit? If only one cell can, that’s your placement, even if that cell still has multiple candidates pencilled in.
Example: in row 4, you’ve pencilled candidates into empty cells. Cell A has candidates {1, 4, 9}. Cell B has {4, 7}. Cell C has {1, 9}. The candidate 7 appears in row 4 only at Cell B. So Cell B must be 7 it’s a hidden single.
Hidden singles unlock most “medium” puzzles entirely. Practice the scan and they start to jump out.
What to do when you’re really stuck
First: don’t guess. The temptation is to pick a cell with two candidates and try one, but guessing in sudoku is slow, error-prone, and you don’t learn anything from it. Almost every well-formed puzzle has a deductive solution. You just haven’t spotted it.
When stuck, try these in order:
- Make sure your pencil marks are accurate. A wrong candidate sends you down the wrong path.
- Pick the digit you’ve placed the most of and look for one more placement.
- Walk through each box one at a time. Each box needs all 9 digits, which ones are missing, and can any be forced?
- Take a five-minute break. Coming back fresh produces breakthroughs more reliably than grinding the same scan for ten minutes.
When all four fail, you’ve probably hit the wall between easy and intermediate. That’s when techniques like naked pairs, pointing pairs, and X-wings come in. We’ve got a separate guide for those when you’re ready, how to solve hard sudoku.
How long “should” an easy puzzle take?
Realistic times for someone playing for the first month:
- Easy, 5 to 12 minutes. If you’re consistently under 6 minutes, move to medium.
- Medium, 10 to 25 minutes. The leap to medium is the biggest jump because pencil marks become necessary.
- Hard, 20 to 50 minutes. You’ll need hidden singles and probably pointing pairs.
- Expert and Extreme, once you’re comfortably under 30 minutes on hard, give expert a try. Extreme can take an hour. That’s normal.
Don’t treat times as a benchmark, treat them as a signal. If easy takes forever, you’re missing naked singles. If hard breaks you, you’re missing pencil marks. The fix is always to slow down and look harder, never to guess faster.
When to move up a difficulty
You’re ready for the next tier when:
- You can solve three puzzles in a row at your current tier without making mistakes
- You can solve them without backing up or erasing
- You finish under the upper end of the time range above
Don’t skip levels. The techniques compound: medium practice teaches you the pencil-mark scan, which is what makes hard solvable, which is what makes expert possible.
One last thing, the mindset
Sudoku rewards patience over speed. The best solvers aren’t the fastest scanners, they’re the ones who don’t place a digit until they’re certain. One wrong placement in a hard puzzle can poison the rest of the solve and you might not catch it for 20 minutes.
Slow down. Pencil-mark thoroughly. Move only when you’ve provena placement, not when you’ve guessed it. That’s the entire skill.