🧐Learn Sudoku Easily: H5 How‑to from Beginner to Pro

Sudoku is a logic number puzzle loved worldwide. It helps you pass time while effectively training observation, focus and reasoning.

🎯 What Is Sudoku? Goal Overview

The goal is simple, yet achieving it can be challenging.

  • Board: You face a 9×9 grid split into nine 3×3 boxes (also called subgrids).
  • Task: Fill all 81 cells with digits 1–9.
  • Start: Some digits are prefilled. Use pure logical reasoning to fill the rest.

📜 Sudoku’s Three Core Rules

RuleDescription
Rule 1: No row duplicatesIn any of the 9 rows, digits 1–9 must appear exactly once.
Rule 2: No column duplicatesIn any of the 9 columns, digits 1–9 must appear exactly once.
Rule 3: No box duplicatesIn any 3×3 box (9 boxes total), digits 1–9 must appear exactly once.
💡 Core takeaway: Each digit 1–9 must be unique in any row, column, and 3×3 box.

🚀 Newbie Essentials: Two Key Techniques

Technique 1: Elimination (single‑cell pinpoint)

Use the three core rules to eliminate impossible digits for a cell until only one candidate remains.

  1. 🔍 Focus high‑density areas: prioritize 3×3 boxes that already contain 5+ digits—rich clues make breakthroughs easier.
  2. ❌ Eliminate by row/column: remove digits already present in the target cell’s row and column.
  3. ❌ Eliminate by box: remove digits already present in the cell’s 3×3 box.
  4. 🎯 Lock the unique value: from 1–9, subtract all eliminated digits. If only one remains, that’s the answer.

Example: A cell is at row 5, column 4, inside the middle‑left 3×3 box.

• Row 5 has: 1, 3, 4, 7

• Column 4 has: 2, 5, 8

• Box has: 1, 2, 9

• Eliminated set: {1, 2, 3, 4, 7} ∪ {2, 5, 8} ∪ {1, 2, 9} = {1, 2, 3, 4, 5, 7, 8, 9}

• Remaining digit: 6. (You found the unique solution!)

Technique 2: Box‑locking (band/stack elimination)

Locate a digit within a 3×3 box using band/stack logic—consider the grid as 3 big rows (bands) and 3 big columns (stacks).

  1. Pick a target digit N to locate.
  2. 🔎 Observe a band or stack: among its three boxes, find where digit N already appears in two boxes.
  3. 🔒 Lock the third box: if N appears in the first two boxes of the band/stack, it must also appear in the third box.
  4. After row/column elimination:
    • Check which rows are occupied by N in the first two boxes.
    • In the third box, N cannot be placed in those rows again.
    • This often narrows down N’s location to a single cell in the third box.

Example:

• The top band contains the left‑top, middle‑top and right‑top boxes.

• Digit 5 is in row 1 of the left‑top box.

• Digit 5 is in row 3 of the middle‑top box.

• Therefore in the right‑top box, 5 can only be in row 2. Then scan its three cells to exclude columns already occupied by 5 and find the unique position.

Start Your Sudoku Journey

You now know the core rules and basic tips. Whether relaxing or training on the go, our H5 site offers difficulties from beginner to master.

👉 Jump in and solve your first Sudoku now!

Sudoku FAQ

QuestionAnswer
Does a standard Sudoku have exactly one solution?Yes. Well‑designed puzzles have a unique solution.
Do I need to guess?No. Sudoku must be solved by logic; if you feel forced to guess, the puzzle may be too hard or you need advanced techniques.
Can I use pencil marks?Absolutely. Use candidate numbers to note possible digits—crucial for hard puzzles.