Bulls and Cows (paper and pencil game)

Bulls and cows is a traditional English  pencil and paper game for two players whose objective is to guess a  four digit secret number. All digits must be different. Nothing else than paper and pencil are needed.

On a sheet of paper one player writes down the secret number.
On another sheet of paper the opponent has to guess the number in different successive tries, each try receives a public evaluation from the owner of the secret number. A right digit on the right place is a bull, a right digit on the wrong place is a cow.


     Secret number: 4271
    tries         number      scores
      1            1234         1B2C       (1 bull and 2 cows,  "2" is bull, "4" and "1" are cows.)
      2            5678         1B0C
      3            9012         0B2C
      4            9087         0B1C
       .             ......           .......
       .             ......           .......
      8            4271         4B0C

Once the number is guessed the player roles are inverted, the owner of the secret number has to guess and the player who guessed writes down a new secret four digit number. The winner is the player with less tries in finding the right number.
The game can also be played by two teams of  2-3 players, team members share their thoughts before they take a decision.
Instead of a four digit secret number it can be also a 3-6 digit secret number. The more digits, the more difficult is the game.
The game Mastermind  is Bulls and Cows without a plastic board and coloured plastic pins.

Wikipedia article about Bulls and Cows
More Paper and pencil games