How to play
- Tap digits, or type them, to fill in your guess. The daily code has four digits from 1 to 6.
- Press Try it to see the result.
- Read the dots: ● for a right digit in the right place, ○ for a right digit in the wrong place.
- Use what you learned to make a better guess. Crack the code in 10 tries to win.
In practice mode you can choose Easy, Normal or Hard. Hard has five digits from 1 to 8, which leaves over 32,000 possible codes.
A strategy that works
Random guessing wastes tries. Treat each guess as a question.
- Open with two pairs. A first guess like 1 1 2 2 tests two digits at once, and it tells you more than four different digits would.
- Count first, place later. Add up the dots to find out which digits are in the code. Then work out where they go.
- Change one thing at a time. If you swap two digits and the dots change, you know something about those positions.
- Use a digit you have ruled out as a blank. If 6 got no dots, then 1 6 6 6 tests only whether the first digit is 1.
- Never repeat a guess that cannot be right. Before you submit, check that it fits every result so far.
The maths behind it
The daily code has 1,296 possibilities: six choices for each of four positions. In 1977, computer scientist Donald Knuth showed that the board game version with these same numbers can always be solved in five guesses or fewer. Our daily gives you ten, so there is room for mistakes.
More games
Try Cipher Sprint for a race against the clock, or the daily cryptogram for a slower word puzzle.