Objective / Rules - Complete the grid such that every row and column contains the digits 1 to the size of the grid. - Each row and column contains each digit only once. - A cage clue tells you the answer after the cage values have undergone the specified mathematical operation. - The clue doesn't tell you which way around the digits occur, just the answer to the calculation. - A digit can appear more than once in a cage.

Pencil Marks What is a pencil mark? Pencil marks can help you keep track of your own thinking, simply enter more than one digit/letter into each square, just like you might do if you were using pen and paper. The size of the digits/letters is smaller when there is more than one digit/letter in a square. A square might contain more pencil mark digits/letters than can be shown.

Keyboard Usage[only when your cursor is in the grid] Note: only when supported by your computer/device/browser/etc. A = auto-pencil marks (or click the check box). CTRL + arrows = move around the grid. SHIFT + number = highlight all squares with that number [SHIFT+0 to clear].

Checking If you click 'Check' the system will check for incorrect squares. If 'Show mistakes when checking' is checked they will be marked in red. There are two types of error checked for: 1. A single number that isn't the same as the solution. 2. Multiple numbers that don't contain the solution number.

Uniqueness Each puzzle has exactly one solution, which can be found using logic alone and no guesses are ever required. If you think you've found another solution, then please double check the rules.