Early 2009, I read about KenKen (also known as **Calcudoku**) in the
New York Times, and decided to write a program that creates similar puzzles, and put them online.
Calcudoku puzzles are similar to Sudoku, but also require some basic math skills to solve.

The rules are:

- the 4×4 puzzle uses the numbers 1-4, the 6×6 the numbers 1-6, and so on
- in each row and in each column each digit can appear only once (just like in Sudoku)
- each "cage" (the blocks with the thick border) shows a result and an operation (addition: +, subtraction: -, multiplication: ×, or division: :). The operation applied to the numbers in the cage should produce the result shown. Note that for subtraction and division the order is not fixed (!)

Look at the solutions of earlier days to make things clearer.

Brief explanations of the special operators (e.g. `^` for exponentiation) is given
below the puzzles with these operators.

You can solve the puzzle on the page using the arrow and number keys, or using the mouse. Use the spacebar to clear a cell. Use backspace to undo a move. Press '=' to highlight the number in a cell. In the largest puzzles (10x10 Calcudoku puzzle (every Tuesday and Friday) and 12x12 (every Sunday and Thursday)), simply press 1 then 0, or 1 then 1, or 1 then 2 to enter 10, or 11, or 12. You can also use the a, b, and c keys to enter 10, 11, or 12. Press the Shift key and a number to store it as a guess.

You can now do the puzzles on Facebook (you can combine your facebook account with this one, and keep using both).You can also solve the puzzles on the *iPhone/iPod Touch/iPad*.

Every puzzle has a single solution.

This type of puzzle is known as Calcudoku, Newdoku, Rekendoku, MathDoku, Kashikoku-Naru, KenKen, Kendoku, Sumdoku, Calkuro, K-Doku, Keen, NekNek, CanCan, Square Wisdom, Emono, Minuplu, LatinCalc, Yukendo, ArithmeGrid, Hitoshii, Inky, SquareLogic, TomTom, and if you know of any other names, let me know`:-)`. The "no-op" puzzles are sometimes called "Mystery Calcudoku". Of these names, "KenKen" and "KenDoku" are trademarks of Nextoy LLC.

**Note**that this is a hobby site, and is not affiliated with Nextoy nor their brands.

A Killer Sudoku is the same as a Calcudoku puzzle, except:

- the operator is always + (and not shown)
- every 3×3 box has the numbers 1..9 exactly once
- a cage also can
*not*have duplicate numbers (!)

You can solve the puzzle using the number + arrow keys, or the mouse. Use shift + number to toggle guesses, the space bar to clear a cell, and 'backspace' for undo. Press '=' to highlight the number in a cell.

You can solve the puzzle using the number + arrow keys, or the mouse. Use shift + number to toggle guesses, the space bar to clear a cell, and 'backspace' for undo. Press '=' to highlight the number in a cell.

These Sudoku puzzles were created using Mogens Kjær's Sudoku generator.