Do you need math to solve sudoku?

No. The digits are only symbols; you could use letters or colors instead. Sudoku is pure logic about where each symbol can go.

What is the first thing to do in a sudoku?

Pick the digit that appears most often in the givens and scan each box for the one place it can go. Those hidden singles are usually the quickest wins.

Can every sudoku be solved without guessing?

Every well-made sudoku has exactly one solution and can be solved by logic. Very hard grids may need advanced techniques, but never a blind guess. Every puzzle on Silvera PuzzleClub is checked to have a single solution.

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How to Solve Sudoku: A Step-by-Step Guide for Beginners

To solve a sudoku, fill each empty cell so that every row, column and 3×3 box contains the digits 1 to 9 exactly once. You never need to guess: look for a cell where only one digit fits, or a digit that fits in only one cell of a row, column or box, write it in, and repeat.

By the Silvera PuzzleClub team · Updated October 30, 2026 · Play now

The rules in one minute

A sudoku grid has 81 cells arranged in 9 rows, 9 columns and nine 3×3 boxes. Some cells already contain digits; these are called givens. Your job is to fill the rest so that each row, each column and each box contains every digit from 1 to 9 once. A well-made sudoku has exactly one solution, and it can always be reached by logic.

The three kinds of unit: a row (shaded across), a column (shaded down) and a 3×3 box (top left). Each must contain 1–9 once.

The words row, column and box are often grouped together as units. Every cell belongs to exactly three units, and the 20 other cells that share a unit with it are called its peers. A digit placed in a cell can never appear again among its peers. Almost every technique in sudoku is a way of using that one fact.

Step 1: Scan for hidden singles

Pick a digit, say 5, and look at one box. Follow every 5 that is already on the board across its row and down its column. Each of those lines rules out cells in the box you are studying. If only one empty cell in the box is left that a 5 could go into, the 5 must go there. This is called a hidden single: the cell might have other possible digits, but the 5 has nowhere else to go.

The 5s in the first two boxes rule out the top two rows of the third box. The bottom row of that box has only one empty cell, so the 5 goes there.

Work through the digits 1 to 9 one at a time and sweep each box, then each row and column. On an easy puzzle, scanning alone will carry you a long way.

Step 2: Look for naked singles

Sometimes it is easier to look at a single cell and ask which digits it can still hold. Check its row, its column and its box. If eight different digits already appear among its peers, the ninth is the only one left. That is a naked single. Rows, columns or boxes that are nearly full are the best places to look.

Eight digits are already in this row. The only digit missing is 6, so the empty cell must be 6.

Step 3: Use pencil marks

When scanning stops giving you new digits, write the possible digits, called candidates, in small numbers in each empty cell. Our puzzles have a Notes button for this (or press N). Placing a digit automatically removes it from the notes of its peers, so the board keeps itself tidy.

Pencil marks turn a hard search into a visible pattern. A cell with one candidate left is a naked single. A digit that appears in only one cell of a unit is a hidden single. And once you can see the candidates, intermediate techniques such as pairs and pointing become possible. They are explained in our sudoku techniques guide.

A simple routine that works

Scan digits 1 to 9 across every box for hidden singles. Start with the digit that already appears most often.
Check nearly full rows, columns and boxes for naked singles.
Repeat steps 1 and 2 until nothing new appears. Each digit you place opens new moves.
Fill in pencil marks for the remaining cells.
Look for pairs and pointing (see the techniques guide), then go back to singles.

On our site, Easy and Medium grids can always be finished with steps 1–3. Hard grids need step 5 at least once, and Expert grids need more advanced patterns. Every rating is checked by software that solves the grid the way a person would.

Common mistakes

Guessing. A guess that happens to be wrong may not show up as a conflict until much later. If you are stuck, add pencil marks instead.
Forgetting the box. It is easy to check the row and column and miss the 3×3 box.
Stale notes. If you keep notes on paper, remove a candidate from every peer when you place a digit.

Frequently asked questions

Do you need math to solve sudoku?: No. The digits are only symbols; you could use letters or colors instead. Sudoku is pure logic about where each symbol can go.
What is the first thing to do in a sudoku?: Pick the digit that appears most often in the givens and scan each box for the one place it can go. Those hidden singles are usually the quickest wins.
Can every sudoku be solved without guessing?: Every well-made sudoku has exactly one solution and can be solved by logic. Very hard grids may need advanced techniques, but never a blind guess. Every puzzle on Silvera PuzzleClub is checked to have a single solution.