Sudoku
A number puzzle in big, clear print, with four levels from gentle to hard.
The aim
Fill in the grid so that every row, every column and every box holds each of the numbers 1 to 9 exactly once.
How the grid is laid out
- The grid has nine rows and nine columns of squares, 81 squares in all.
- Thick lines divide it into nine boxes, each three squares by three.
- Some numbers are already filled in when you start. They are part of the puzzle and can't be changed.
How to play, step by step
- Tap an empty square to choose it. It turns yellow, and its row, column and box are shaded lightly.
- Tap a number on the number pad to write it in the square. The numbers you write are blue, so you can tell them from the ones you started with.
- To rub a number out, tap it again on the pad, or tap Clear.
- If the same number is written twice in a row, column or box, both turn red and get a red frame, so you can spot the slip.
- Keep going until every square is filled in. When the grid is complete and nothing is red, the puzzle is solved.
Pencilling in notes
On harder puzzles it helps to note down the numbers a square might hold.
- Tap Notes on the number pad, so it says "Notes: on".
- Now each number you tap is pencilled into the square in small print. Tap it again to rub it out.
- The number pad shows the chosen square's notes in big print: those keys get a blue frame.
- When you write a number in, its notes in the same row, column and box are rubbed out for you.
- Tap Notes again to go back to writing numbers.
Four levels
- Gentle starts with 40 numbers filled in. A relaxed way to begin. Play a gentle puzzle.
- Easy starts with about 32 numbers. Every missing number can be found by looking along a row, a column or a box. Play an easy puzzle.
- Medium gives as few numbers as it can, so you will need to look harder, but still no notes are needed. Play a medium puzzle.
- Hard puzzles need notes and some cleverer reasoning. Play a hard puzzle.
Every puzzle at every level has exactly one answer, and it can be reached by reasoning alone. You never have to guess.
Tips
- Start with a number that is already in the grid many times. Look at each box that doesn't have it yet, and see how many squares are left where it could go.
- Look for a row, column or box that is nearly full. The last few numbers are often easy to find.
- Tap a number in the grid to choose its square: every square with the same number is shaded blue, which makes it easy to see where that number still has to go.
Puzzle numbers
Every puzzle has a number, shown at the top of the screen. The numbers go from 1 to 1,000,000 at each level. The same number is always the same puzzle, so you can play one again or share it with a friend.
Playing here
- Undo takes back any move, as many as you like.
- Restart clears your numbers and starts the same puzzle again; New game gives you a different one.
- With a keyboard, the arrow keys choose a square, 1 to 9 write a number, Delete rubs it out and N turns notes on and off.
- There is no timer and no score. Take as long as you like.