How to play Sudoku

The goal of Sudoku is to fill in a board of 9×9 squares with numbers so that
each column, row, and 3×3 block contain the numbers between 1 to 9.
At the beginning of the game, the board will have some of the squares
filled in. Your job is to use logic to fill in the missing numbers and
complete the grid. Don’t forget, a move is incorrect if:

- Any row contains more than one of the same number from 1 to 9
- Any column contains more than one of the same number from 1 to 9
- Any 3×3 block contains more than one of the same number from 1 to 9

You can play 5 new Sudoku puzzles every day with levels ranging from Very Easy to
Very Hard. We hope you'll enjoy some fun and challenging Sudoku puzzles.

Keys & Buttons

To play this game you can use a combination of game buttons and keyboard keys.

**Game Buttons**

Reveal the correct number for the marked empty field

Reveal the correct number for a random empty field

Check the board and mark errors with red

Show solution for this puzzle

Print this Sudoku on paper

**Keyboard Keys**

Delete number in marked field
Delete number in marked field (backspace)
Tips & Tricks

Great satisfaction is often the reward after having solved a Sudoku puzzle. Especially if it
has been a particularly tricky one.

Sudoku is a logic game. Applying strategies to logic games will help you solve Sudoku puzzles
more quickly. You probably already use some strategies without thinking of them as
strategies. In this section we'll introduce 6 basic strategies.

A traditional Sudoku puzzle consists of a board of 9x9 cells as seen in the picture below.
This board has rows (A), columns (B), and blocks (C). Each cell can have a number from 1 - 9.
Possible numbers in a cell are called candidates.

The basic strategies often mention these terms: rows, columns, blocks, and candidates.

The first two of the six basic strategies are used to savely determine a number in a given cell.
The last four strategies are used to eliminate numbers.

**Naked Singles**
This is the simplest strategy. If a cell in a row only can have a single candidate number,
let it be number 5, then this number (5) must go in that cell. This strategy also applies
to columns and blocks.

**Hidden Singles**
Same as Naked Singles but the same cell can have other candidates as well but they can be
removed because the Hidden Single must go in this cell.

**Naked Pairs**
Same logic as Hidden Singles but now we are talking about two numbers instead of one. If a pair
of numbers in a row can only appear in two cells you can savely remove the same two numbers if
they are present in the same two cells' column and block. This is also true for Naked Pairs
appearing in a column.

**Hidden Pairs**
Just like Naked Pairs but with an extra twist. Now, the cells with Naked Pairs also have other
candidates. But as we know that the Naked Pairs must reside in these two cells, we can savely
remove the other candidates.

**Naked Triples**
Building on top of the strategy of Hidden Pairs we have Naked Triples which can be a little
tricky to spot. If three numbers are candidates in three cells inside a row
then for each of the three cells you can remove the same numbers if they are candidates in
other cells column- and block-wise. What makes this tricky is that all three numbers need not
be candidates in the same cell. Let's say you have three cells sharing the candidates: 4, 5, and 6.
They are distributed in this way: 45, 56, 46. This setup is also called Naked Triples.

**Hidden Triples**
Again same logic as the previous strategy. However, this time the cells also have other candidates.
This simply means you can savely remove these other candidates.

Games like Sudoku?

Just like physical exercise, your mind needs some exercise, too. Doing Sudoku is a great and fun way
to do so. However, Sudoku is not the only brain games available. There are many other brain games that
can pump up your brain such as crossword puzzles, Wordfeud, Rubiks Cube, and Worduku just to mention
a few.

**Crossword puzzles**
This is one of the best known brain game and comes in all kinds of difficulties. Doing crosswords regularly
improves your vocabulary and strengthens your memory.

**Wordfeud**
This brain game took the app world by storm. Wordfeud was launched in August 2011 and quickly gained hugh
popularity. It's inspired by the traditional board game Scrabble where you lay down tiles of letters next
to each other to form a word.

**Rubiks Cube**
Originally called Magic Cube was invented in 1974. Its mainstream popularity peaked in the 1980s and is
considered the world's top-selling puzzle game. A traditional Rubiks Cube is covered with multicoloured squares,
which the player attempts to twist and turn so that all the squares on each face are of the same colour.

**Worduku**
Like Sudoku, Worduku uses letters instead of numbers. The rules and strategies used is just like Sudoku.