Number Fill Puzzle Online: Complete Rules and Strategy Guide

Game Overview

Number Fill is a classic logic puzzle also known as a Latin Square puzzle. Your goal is to fill every empty cell with a number so that each row and column contains every number from 1 to N exactly once. Simple rules, deep logic.

How to Play Number Fill

• Each puzzle is an N×N grid with some numbers already filled in as clues.
• Fill each empty cell with a number from 1 to N.
• Every row must contain each number exactly once — no repeats allowed.
• Every column must contain each number exactly once — no repeats allowed.
• Use logic and elimination to determine the correct placement for each number.

Controls

• Click or tap a cell to select it, then click a number button or press a number key to place it.
• Use arrow keys to move your selection across the grid.
• Press Delete or click the ✕ button to erase a cell.
• Click Check to verify your solution, or Hint for help finding the next move.
• Click Undo to reverse your last move.

Scoring

• Your time is tracked from the moment the puzzle loads.
• Fewer moves and less time means a better performance.
• Using hints does not disqualify you, but try solving without hints for the best experience.
• Each difficulty level provides a different challenge — master Easy before moving to Hard.

Tips and Strategies

• Scan for singles: Look for rows or columns with only one empty cell — the missing number is your answer.
• Use elimination: For each empty cell, note which numbers are already in its row and column. If only one number remains, that is the answer.
• Work in pairs: When two cells in a row share the same two candidates, those numbers can be eliminated from other cells in that row.
• Start small: Begin with 4×4 puzzles to learn the logic before tackling larger grids.
• Check often: Use the Check button to catch errors early before they cascade.

Frequently Asked Questions

How is Number Fill different from Sudoku? Number Fill uses only row and column constraints. Sudoku adds the extra rule that each 3×3 box must also contain all digits 1-9.

Does every puzzle have a unique solution? Yes. Every puzzle generated by this game is mathematically guaranteed to have exactly one valid solution.

What grid sizes are available? We offer 4×4, 5×5, 6×6, and 7×7 grids, each with Easy and Hard difficulty levels. Larger grids have more possibilities and require deeper logic.

Can I play on my phone? Absolutely. The game is fully responsive and works on any device with a modern web browser.