Calcudoku

This style of puzzle was invented in 2004 in Japan by math teacher Tetsuya Miyamoto as a form of self-help brain training. The original names (KenKen and KenDoku) are derived from the the Japanese for 'cleverness'. First publication outside of Japan was in 2008 in The Times, in the UK. Since then the puzzle style has grown in popularity and is widely published in newspapers, magazines and online globally, as well as being used as a teaching tool by many teachers.

Calcudoku retains the Row and Column constraints of Sudoku (forming a Latin Square) and combines them with irregular regions, each assigned an arithmetic operation (+, -, x, ÷) that must be satisfied. One key difference from Killer Sudoku is that numbers can repeat in the irregular regions.

The + and x operations give the same answer no matter what order the numbers are processed in. For the - and ÷ operations the numbers should be processed in descending order.

Here at Hardcore Puzzles we aim to bring your some of the more challenging Calcudoku puzzles available, including those where the operations are not given at all and must be derived as part of the solution. Here are our latest Calcudoku books...