If a cell contains two or more numbers, they will automatically become notes. If you only want one note, enter the number then press the P key, or the note button on touchscreen devices:

This is a fantastic technique to jumpstart the game and place some of the first numbers on the grid. Once you have them, you can continue unraveling the ball and placing more and more numbers. Why you should play Killer Sudoku The two vertical cages in the top left of the top right nonet cannot be 2+2 as that would mean duplicates, so they must be 1+3. The 1 cannot be in the top line as that conflicts with our first 2 cells therefore the top cell of this pair is 3 and the lower cell 1. This also means the 3 cell cage 15 to the left cannot contain a 3 and so is 4+5+6. You earn a point for every puzzle you've solved. At various levels - 1 puzzle, 10 puzzles, 25 puzzles, etc. - your avatar will be adorned with a new badge in recognition of your achievement. In the early stages of the game, the most common way to begin filling in numbers is to look at such low-sum or high-sum cages that form a 'straight line'. As the solver can infer from these that certain numbers are in a certain row or column, they can begin 'cross-hatching' across from them. No number appears more than once in a cage. (This is the standard rule for killer sudokus, and implies that no cage can include more than 9 cells.)In Killer Sudoku there’s a new concept of a “cage” – a group of cells within a dotted line that make up a sum shown as a small number above. Like in Sudoku, your ultimate goal is to fill the grid with numbers, while paying attention to ”the sum rule”. Let’s review Killer Sudoku rules in detail below. How to play Killer Sudoku With 6-cell, 7-cell or 8-cell cages, correlating the combinations with their 3-cell, 2-cell, or 1-cell complements usually simplifies things. The table for 6 cell cages is the complement of the 3 cell table adding up to 45 minus the listed value; similarly, the 7 cell table complements the 2 cell table. An 8-cell cage is of course missing only one digit (45 minus the sum of the cage). The four cells in the top right cage (totaling 15) can only include one of 1, 3, 7, or 9 (if at all) because of the presence of 1, 3, 7, and 9 in the top right hand nonet. If any one of 1, 3, 7, or 9 is present then this must be the lone square in the nonet below. Therefore, these 4 cells are one of 1+2+4+8 or 2+3+4+6. So what’s the first thing you should do when starting off with the completely empty grid? First and foremost, you need to always keep in mind the“45 rule”.

The FILL button (or F key) enters all numbers into the highlighted cells. If fill uses cage combinations is enabled (via the Preferences menu), then it only adds numbers that appear in the respective cage combinations, otherwise it adds all numbers from 1 to 9.

As you browse through the archives, you'll be able to see which puzzles you've solved and your solving times. Patreon

Killer Sudoku is a fun twist on the classic sudoku for those of you seeking something new and challenging. It’s also known by such names as sumdoku, addoku and sumoku puzzle but in a nutshell it’s pretty much the same number puzzle. What’s the difference between Sudoku and Killer Sudoku? Killer sudoku puzzles were already an established variant of sudoku in Japan by the mid-1990s, where they were known as "samunamupure." The name stemmed from a Japanized form of the English words "sum number place." Killer sudokus were introduced to most of the English-speaking world by The Times in 2005. When the highlighted cells all belong to the same cage, the Combinations control shows its cage combinations. It updates automatically as you move between cages.puzzles and two “greater than” sudoku puzzles and one “greater than-killer” sudoku puzzle. You can play Notes/pencil marks are small numbers that you can enter into cells when you aren't yet sure of the final answer. You can update all of the highlighted cells together by using the keyboard or the touchpad as normal. What is auto-sum? offline. Older puzzles are in the archives. Older puzzles are also listed by difficulty. Generally, the weekly puzzles are harder than the daily puzzle. Have Fun! For example, consider a 2-cell cage with a sum of 5 - its cage combinations are 1 4 and 2 3. If fill uses cage combinations is enabled, the FILL button will only add the numbers 1 2 3 4 to cells within the cage. Multi-cell selection