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## Nonconsecutive Sudoku

In a nonconsecutive sudoku, adjacent numbers (horizontally or vertically) cannot be consecutive.

Let’s take a look at an example: Let’s look at B5 (the middle box), and consider where the number 5 might be: • R4 and C4 (shaded pink) already have 5s.
• Neither of the cells below and to the right of the number 6 in the middle (shaded blue) can have 5, according to the rule of nonconsecutiveness.
• Only one possibility is left in B5: R6C6.

The same method can be used to place the number 4 in B2 (the top middle box).

Download this puzzle as a PDF, print it and try to solve it yourself!

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## Tele-Sudoku • Standard sudoku rules apply.
• Pairs of cells in corresponding positions in two boxes are shaded. The numbers in these cells should be the same. The red lines mark some examples of corresponding positions where the numbers should be equal.

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## Dot Sudoku

This is an extension of consecutive sudoku.

• Normal sudoku rules apply.
• A white dot between two cells signifies that the difference between them is 1 (in other words: the two numbers are consecutive).
• A black dot between two cells signifies that one number is twice as large as the other.

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## Consecutive Sudoku

• Normal sudoku rules apply.
• A mark between two cells signifies that the two numbers in the cells are consecutive; the difference between them is 1. (For example: 1 and 2, or 6 and 7.)

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## X-Sudoku

In normal X-sudoku puzzles the two diagonals are marked with a thin, gray line. (They might also be shaded, but that’s less common.)

The lines signify that the sudoku rule of no repeated number also goes for the diagonals. An X-sudoku puzzle. In addition to normal sudoku rules, no number can be repeated in the diagonals either.

Some puzzles might have more than two lines. The rule is the same: No number can be repeated in any of the diagonals. An X-sudoku with more than two diagonals. This variant is called “snowflake”. No number can be repeated in any of the diagonals.
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## Greater Than Sudoku

“Greater than” sudoku have no givens. Instead, there are “greater than” symbols to help you deduce where the different numbers must be. A “greater than” sudoku.

Consider R5C8 in this example: If we follow the “greater than” symbols from cell to cell, we see that all the other numbers in the same box must be bigger. Thus, R5C8 must be 1.

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## Extra Group Sudoku

In sudoku puzzles with an extra group of cells (marked by shading the cells in the group), the rule about no repeated number also applies to that group.

The group is often arranged in a symmetrical pattern, like in the example below. Categories

## Double Sudoku

A double sudoku is made up of two standard sudoku puzzles overlapping. Each of them cannot be solved on its own; you have to use clues from one puzzle to solve the other, and vice versa. A double sudoku—two overlapping puzzles.
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## Killer Sudoku

Killer sudoku, also called sum sudoku, have no given numbers. Instead, there are sum cages—extra boxes with numbers that are the sums of the numbers inside those boxes.

Like the normal sudoku rows, columns and boxes, no number can be repeated in the sum cages.

Example: The cage sum 4 can only be the sum of 1+3, not 2+2. A cage of three cells with the sum 6 can only be 1+2+3, not 1+1+4.

Killer sudoku is a SudokuMix favorite. There are many different solving techniques to discover, and the puzzles are often very satisfying to solve. A killer sudoku example.
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## Jigsaw Sudoku

Jigsaw sudoku puzzles are just like regular sudoku, except that the boxes have irregular shapes.