This method won't help you pencil in any new numbers, but it will help you nail a number down within a specific row or column. The example shows that the number 7 can only be inserted in the red cells of the middle row. Thus you can remove 7 as a possible candidate from the rest of the row. In this example, if you put the number 3 in the starting cell, you will see that the above-right neighboring cell must contain a 9. Now, try and enter a 6 in the starting cell instead, and move the other way around, entering candidate values. When you reach the above-right neighboring cell again, you will find it must contain a 9 this time around too. Thus this cell must contain a 9. In addition to the standard Sudoku rules of every row, column, and 3×3 region containing the numbers 1 to 9 once and only once each, Arrow Sudoku only has one additional rule.

Understanding this will help you with solving Sudoku puzzles and also give you a better appreciation for the game. Do not repeat any numbers This method can work when you look at cells comprising a rectangle, such as the cells marked in red. In this example, let's say that the red and blue cells all have the number 5 as candidate numbers. Now, imagine if the red cells are the only cells in column 2 and 8 in which you can put 5. When solving arrow sudokus, it can be particularly useful (in a 9x9 puzzle) to see if there are any 9's that you can place right away based on the direction and location of the arrows. In most Arrow Sudoku puzzles each circled cell will only have a single arrow originating from it. However, there is nothing stopping there being multiple arrows coming out of the same cell. It can take a while to start placing numbers with arrow sudoku as you go about working out the various options for each cell, but once you get going the puzzle soon builds momentum and there is lovely solving interplay between the arrows and their values and the standard sudoku rules.

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Because of the arrow regions in the puzzle, you will need more than just sudoku logic to solve arrow sudoku. You must also look at the possible values within the arrow: both for the total cell (circled) and the cells along the path of the arrow. It is this combination of sudoku logic with the interesting and sometimes subtle deductions that can be made from the arrow regions that make this such a compelling and interesting puzzle. All arrow sudoku have one solution that can be reached through logic alone: no guessing is required.

My method was to create a larger sudoku grid in Word, and in very small light type at the top of each box, put the numbers 1-9 (so they fit in one row, evenly spaced out). Then I re-drew the circles and arrows and given numbers in pen. The circle at the top of each arrow contains a number that is the sum of the numbers that appear along the body of the arrow, ending in the square with the arrow head.How do you recognize a swordfish pattern? You look for cells with common candidate numbers that can be chained together like in example D. If you start on, say, the top-left red cell. Then you draw a line either vertically or horizontally until you reach another cell containing the same candidate number. Then you repeat this pattern until you return to the original cell. If you reach the original cell, you have a swordfish pattern!

Swordfish is a more complicated version of X-Wing. In most cases, the technique might seem like much work for very little pay, but some puzzles can only be solved with it. So if you want to be a sudoku-solving master, read on! These are fiendish! I have sometimes found help from the following. Where three numbers which are all different add to a circle, there are only seven combinations, adding to between 6 and 9. All but one of them contain '1'. In addition, the grid contains grey arrows. The number to be placed in the circled cell at the start of each arrow is the sum of the digits that fall along the path of the arrow. Arrow Sudoku is a variation on sudoku, which you may also know as Sudokuarrow. But if you've never come across this fascinating puzzle before, then take a look at the grid to the right to see a sample puzzle - it will also reveal exactly why this puzzle has the name that it does! is an achievement. Thank goodness they're not in the i (a great newspaper!) every day. I'd never get anything else done!Thus if you look at the first circle in cell two of the puzzle, the number therein is the sum of the first and eleventh cells of the grid, so if those two cells contain 6 and 3, then the circled cell contains 9, as the sum of 6 + 3 = 9. Arrow sudoku is a visually striking variant of the standard sudoku puzzle, and really adds a very interesting element to the solving mix: arrows that use the numerical values of cells to help you solve the puzzle. Arrow sudoku puzzles will have many fewer givens than a standard sudoku due to the fact that there is much more information to be gained that will help you solve the puzzle from the arrows. Look at example B. We can eliminate 3 as candidate in every cell marked in blue. The reason for this is that if we consider the possible placements of the number 3 in the red cells, we get two alternatives: either you must put 3s in the green cells, or in the purple cells, as example C shows. In any case, each of the columns 2, 4, 7 and 9, must contain a 3 in one of the colored cells, so no other cell in those rows can contain a 3. Look now at the arrow region whose head is the second cell in row 6 (to the right of the given '2'). Note that the body of the arrow goes through 5 cells, and that three of them are in the same region. Since the three cells are in the same region, then the lowest total for them is 1 + 2 + 3 = 6, whilst there are two cells in other regions, so the lowest for those is 1; thus the circled cell contains either 8 or 9, with all other values instantly eliminated. Furthermore, the cells at the start and end of the arrow can contain only 1 or 2, and the three in the middle can only contain 1,2,3,4.

In addition to the arrows, it will immediately be noticed there are many less givens than with a standard sudoku puzzle. But this is compensated by the fact that the arrows provide additional information - if you know how to access that information!In harder arrow sudoku puzzles, you may need to use the fact that you know a number must go inside the arrow but you don't know where, then use that to eliminate it from the rest of the region it fully intersects. When you start solving a new game, you will be able to place different numbers in the same cell without repeating them, but there will only be one number that belongs in the cell. The example shows that row number 1 and row number 5 both have a cell in the same column containing only the candidate numbers 4 and 7. These two numbers appear as candidates in all of the other open cells in that column too, but since they are the only two candidates in rows 1 and 5, these two numbers cannot appear anywhere else in the row, thus you can remove them. In the example, the two candidate pairs circled in red, are the sole candidates. Since 4 and 7 must be placed in either of these two cells, all of the pairs circled in blue, can remove those numbers as candidates. In this puzzle, this means 1 becomes sole candidate in the second row; 2 becomes sole candidate in row 6; and thus, 6 is sole candidate for row number 4.