All 9 large boxes in the puzzle must have every single number, from 1 to 9, with no repetitions.Every single row (horizontal) must have every single number, from 1 to 9, with no repetitions.Every single column (vertical) must have every single number, from 1 to 9, with no repetitions.While all of them are fairly similar, you must follow each rule to the tee in order to solve the puzzle. There are 3 main rules that you must follow in order to play Sudoku. To learn more about this, you can read our Coolmath Games blog which aims to answer the long-debated question – are video games good for you? What are the 3 main rules for Sudoku? According to psychologist Peter Gray, playing games can help increase problem-solving abilities and reasonable decision-making. While there is still debate over how effective Sudoku is at increasing your IQ, it is generally agreed among scientists that games such as Sudoku increase several cognitive functions. You’re still not sure which spot contains the 6 and which contains the 8, but you’ve narrowed it down a lot. You can eliminate the 6 and 8 from the other spots. Find the Naked Pairs When a box has two spots in which you can enter only the same two candidate numbers (let’s say 6 and 8), that’s a good clue! When that happens, take a look at the other spots in that box. If you find one, that candidate must be in the correct spot, regardless of other candidates in that same spot. Once you’ve filled in all the candidates, look for a candidate that appears only once in a particular row, column, or box. Try timing yourself to see how fast you can beat a given puzzle. You can change the difficulty level in Sudoku from beginner to intermediate or advanced if you want to solve more difficult puzzles. Use the orange guide to see which numbers you've already used in each row, column, and box. Use the numbers 1-9 in each of the 9 rows, 9 columns, and 3x3 boxes of the Sudoku grid. To play our free online Sudoku game, use your mouse and keyboard to fill in the blanks by clicking and placing numbers in the grid. While playing this game, you increase your concentration, develop your memory and promote strategic thinking. Sudoku puzzles stimulate your mind and help you practice logical reasoning. Candidates are essential when solving difficult puzzles. Many beginners don’t bother to use candidates, but that’s a mistake. The candidates will appear as little numbers.

You can do this by clicking the button with the large black dot, and then adding candidates to the spot. When solving a puzzle, try filling in empty spots with all the candidates that might fit there. Fill in the CandidatesĪ “candidate” is a number that could fit in a spot, even though other numbers might fit there too. That makes it easier to place the remaining 7s. Use this to figure out which rows, columns, and boxes don’t yet have a 7. You can click a 7 on the board to highlight all five 7s in the puzzle. For example, if the 7 button has a small 5 in the top right corner, that means there are already five 7s on the board. Start with the big numbers that appear most often. Each of these buttons has a small number in the top right corner - that’s the number of times that the big number already appears on the board. Spot the missing numbersīeneath each puzzle are buttons you use to enter the numbers 1 to 9. Once you’ve solved that piece of the puzzle, move on to the next part. Start by focusing on a column, row or box. Any one Sudoku puzzle contains multiple puzzles within it. When solving Sudoku puzzles, players often feel as if they need to solve the entire puzzle from the beginning. Try using the following techniques to solve Sudoku puzzles. To play our free online Sudoku game, tap and hold a number to lock it and you can use it for multiple cells. Use the numbers 1-9 in each of the 9 rows, 9 columns, and 3x3 boxes of the Sudoku grid.

Online sudoku puzzle