Killer Sudoku

Play Killer Sudoku or Sumdoku. Fill the grid with the numbers 1 to 9, such that each row, column and box contains each number only once. Additionally, a Killer Sudoku grid is divided into cages, each cage has its own background color. The values of the cells in a cage must sum up to the total for that cage, shown in the cage's top left corner. The same number cannot appear in a cage more than once.

1. 1

   Each box, row and column must contain each number once - no repeats.

2. 2

   Look at the empty cells and cross out numbers that already appear in that row, column or box.

3. 3

   The number left over is the only one that can go there.

4. 4

   Type the number in, or tap the cell and choose it.

5. 5

   Stop when every empty cell is filled - then check for mistakes.