Strategies, Tips and Hints
Back to the Basics:
While Sudoku puzzles might look impossible at first glance, they can be deceptively simple. You can solve all but the very hardest puzzles without guessing with a few easy Sudoku strategies. From pencilling-in to simple crosshatching, here are some tips and tricks that are guaranteed to help – and you don’t need a degree in math to use them, either.
Let’s start with the basics: a Sudoku puzzle is made up of nine large boxes in a grid, each of which contains nine smaller boxes. The aim is to fit the numbers 1 to 9 into each of the large boxes so that each column and row of smaller boxes in the grid also contains the numbers 1 to 9. Some of the numbers will be filled in before you start, and the harder the problem, the more you’ll have to fill in on your own.
The simplest - and most important - Sudoku strategy is called ‘crosshatching’. Pick a large box and choose any number that’s not already in that box. Then look at where that number appears in the surrounding boxes. In the boxes below and above, imagine columns running through that number. In the boxes to the left and right, imagine rows. Wherever those columns and rows run through the box you picked first up is wherever the number you picked can’t exist. If there’s only one empty space left, congratulations! Write the number in there, since that’s the only place it can be.
Easy Sudoku puzzles can be solved with crosshatching alone. However, if you need a little more help, try looking at entire rows or columns of the smaller boxes. Remember, each row and column has to contain the numbers 1 to 9. If a row or a column has eight out of those nine numbers, the only empty space has to be that missing number.
A more advanced Sudoku strategy is ‘pencilling-in’. When you’re crosshatching or looking at rows and columns, don’t just write in the numbers that have to be there. Whenever you’ve got a number that could be in either of two spaces, pencil that number in the top corner of the space. That way, if one of those spaces gets filled later on with another number, you’ll know that the other space has to be the first number. Don’t worry if this makes your Sudoku puzzle look a little untidy – once you solve it, you can go through and rub out all the little pencil marks.
Finally, once you’ve pencilled in some possibilities, you can use ‘two-number locks’. If you’ve pencilled in two pairs of numbers in the same two spaces of a larger box, you know that no other number could be in either of those spaces. Even though you don’t know what’s in them, you can treat those two spaces as filled when you crosshatch for other numbers. This is a good way to deal with an annoying nearly-empty box: block off most of it, then crosshatch the rest.
Not every Sudoku puzzle will fall quickly to these strategies. However, if you take your time and solve it box-by-box, you’ll very quickly become a Sudoku master.
While Sudoku puzzles might look impossible at first glance, they can be deceptively simple. You can solve all but the very hardest puzzles without guessing with a few easy Sudoku strategies. From pencilling-in to simple crosshatching, here are some tips and tricks that are guaranteed to help – and you don’t need a degree in math to use them, either.
Let’s start with the basics: a Sudoku puzzle is made up of nine large boxes in a grid, each of which contains nine smaller boxes. The aim is to fit the numbers 1 to 9 into each of the large boxes so that each column and row of smaller boxes in the grid also contains the numbers 1 to 9. Some of the numbers will be filled in before you start, and the harder the problem, the more you’ll have to fill in on your own.
The simplest - and most important - Sudoku strategy is called ‘crosshatching’. Pick a large box and choose any number that’s not already in that box. Then look at where that number appears in the surrounding boxes. In the boxes below and above, imagine columns running through that number. In the boxes to the left and right, imagine rows. Wherever those columns and rows run through the box you picked first up is wherever the number you picked can’t exist. If there’s only one empty space left, congratulations! Write the number in there, since that’s the only place it can be.
Easy Sudoku puzzles can be solved with crosshatching alone. However, if you need a little more help, try looking at entire rows or columns of the smaller boxes. Remember, each row and column has to contain the numbers 1 to 9. If a row or a column has eight out of those nine numbers, the only empty space has to be that missing number.
A more advanced Sudoku strategy is ‘pencilling-in’. When you’re crosshatching or looking at rows and columns, don’t just write in the numbers that have to be there. Whenever you’ve got a number that could be in either of two spaces, pencil that number in the top corner of the space. That way, if one of those spaces gets filled later on with another number, you’ll know that the other space has to be the first number. Don’t worry if this makes your Sudoku puzzle look a little untidy – once you solve it, you can go through and rub out all the little pencil marks.
Finally, once you’ve pencilled in some possibilities, you can use ‘two-number locks’. If you’ve pencilled in two pairs of numbers in the same two spaces of a larger box, you know that no other number could be in either of those spaces. Even though you don’t know what’s in them, you can treat those two spaces as filled when you crosshatch for other numbers. This is a good way to deal with an annoying nearly-empty box: block off most of it, then crosshatch the rest.
Not every Sudoku puzzle will fall quickly to these strategies. However, if you take your time and solve it box-by-box, you’ll very quickly become a Sudoku master.
