To solve an X Addoku, use only the numbers from 1 to 9. The numbers in squares linked by a coloured line must add up to the total given in the top left-hand corner of the set of linked squares. No number is repeated in any of these sets of linked squares.

Every number from 1 to 9 must also appear in:

  • Each of the nine vertical columns
  • Each of the nine horizontal rows
  • Each of the nine 3x3 boxes
  • Each of the two diagonals

The totals given in an X Addoku are like clues. Each is a total to a sum. You have to work out which numbers add up to the total to fill the linked squares. Sounds easy, but each answer has to fit in with the other sums around it.

Use Addoku techniques to help you solve the puzzle. For example, a total of 4 in two squares is a unique Addoku Block. It can’t be 2 + 2 because each block of squares can contain only one of each number. So the two squares can have only 1 or 3, though you don’t know in what order the 1 and 3 go until you look at the other sums around them.

Use the mouse to click up (or down) through the numbers 1 to 9 in each square.

The small black arrows on each side of the square tell you whether you are counting from 1 up to 9 (right arrow) or from 9 down to 1 (left arrow).

Using your keyboard, you can type in up to eight practice numbers below the line at the bottom of each box.

Cross-hatching shows when you have correctly completed each row, column, 3 x 3 box, diagonal and set of squares linked by a coloured line. Any practice numbers disappear.

Game Options

PRINT: Click to print the X Addoku puzzle

  • Available to YouPlay Premium Members only
  • Selected puzzles only

SAVE: Click to save the X Addoku puzzle

  • YouPlay Premium Members receive 10 puzzle save slots
  • YouPlay Members receive 3 puzzle save slots

PAUSE: Click to halt the timer if you wish to pause during game play

EXIT: Click to return to the Game Selection page

UNDO: Undo your moves one click at a time

CLEAR GRID: Undo all moves and start the X Addoku puzzle again

Game Features

TOKEN COUNTER: Displays how many tokens you have won during the game

TIMER: The timer starts as soon as you open the X Addoku puzzle

YouPlay BOOST: Boost your score - multiply your points by working faster and smarter

HINTS: Click to add an extra number to help you solve the X Addoku puzzle

  • YouPlay Premium Members receive 5 hints
  • YouPlay Members receive 5 hints