How to play CodeBreaker
Find the hidden 4-digit code from Bulls and Cows feedback — deduce, don't guess. Also known as Bulls and Cows.
The rules
- A secret 4-digit code is hidden.
- Enter a guess. A Bull is a right digit in the right place; a Cow is a right digit in the wrong place.
- Use the feedback from every guess to narrow down the code, and crack it in as few guesses as possible.
- Classic, Puzzle and Strategy modes, with a deduction tracker and hints (Nudge, Strategy, Guidance).
Playing CodeBreaker on Puzzle Solvers
- Choose Classic, Puzzle or Strategy mode.
- Enter a 4-digit guess with the keypad and press Submit Guess.
- Read the Bulls and Cows, and use the deduction tracker to rule digits in or out.
- Nudge, Strategy and Guidance give increasing help if you need it.
A worked example
Guess 1234 → 1 Bull, 1 Cow: two of the digits 1–4 are in the code, one already in place.
Guess 5678 → 0 Bulls, 2 Cows: two of 5–8 are in the code, none in the guessed positions. The code's four digits are now two from 1–4 and two from 5–8.
Strategies
- Spread your first guesses. Guesses with no shared digits (like 1234 then 5678) tell you quickly which digits are in the code.
- Zero is information. 0 Bulls and 0 Cows rules out four digits at once.
- Keep a list. Write the codes still possible after each guess; every new guess should split that list.
- Bulls before cows. Once you know the digits, move them around to turn cows into bulls.
Common mistakes
- Repeating a guess that the earlier feedback already rules out.
- Counting a digit twice: a digit is either a Bull or a Cow, never both.
Where it comes from
Bulls and Cows is a pencil-and-paper code-breaking game more than a century old; it inspired several later board and computer games.
Frequently asked questions
What is the difference between a Bull and a Cow?
A Bull is a correct digit in the correct position; a Cow is a correct digit in the wrong position.
Who is it for?
It is designed around Year 6 logic and deduction, but works for any age.
Can I share a result?
Yes — the Share button copies your result after you crack a code.
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