Here are four MathDoku, or KenKen type puzzles. We've simplified the more traditional version so that this only includes addition. The idea is for the children to work in pairs to complete each 5x5 grid, following the simple rules: - the numbers entered into each 'cell' (squares marked out by darker lines) should total the clue number in the top left-hand corner; - only the numbers 1, 2, 3, 4 and 5 are used; - like Sudoku, numbers only appear on each row or column once. The worksheet here includes four KenKen puzzles (together with answers).