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Codebreaker
Crack the secret four-digit sequence in ten guesses. The clues reveal correct positions and misplaced digits.
Deduction · no account needed
How to play
A hidden code has four digits, each from 1 to 6, and digits may repeat. Enter four digits without spaces. After every guess, you learn how many digits are in the correct position and how many more are correct but in the wrong position.
For example, if the code were 1123 and you guessed 1214, one digit would be in the correct position and two would be correct but misplaced. Try using the feedback to rule out possibilities logically.
Codebreaker strategy
Treat every guess as an experiment. A useful early guess tests several different digits, while later guesses should change as little as possible so you can see which position caused the feedback to change.
- Separate membership from position: first learn which digits are present, then place them.
- Remember repeats are allowed: one digit may appear more than once in the code.
- Use controlled changes: swapping two known digits can reveal whether either belongs in that position.
What skills does it practise?
Codebreaker rewards deduction, elimination and careful use of evidence. It is useful practice for the same habits used in logic-grid puzzles: record what is known, avoid assumptions and make each new test answer a specific question.
For more deduction challenges, try the logic brain teasers or read five reliable brain-teaser strategies.