How to play Bulls and Cows

 Introduction to Bulls and Cows

Bulls and Cows is one of the paper-and-pencil games and old code-breaking games that require one person who sets a secret 4 digit number and a player who tries to guess the 4 digit number. 

Boardgame Mastermind is originated from this Bulls and Cows game.

The numerical version of the game is usually played with 4 digits, but can also be played with 3 or any other number of digits.

Rules in Bulls and Cows

A person needs to write his or her secret code of digit number on a piece of paper while the player will try to guess the secret number.

After every turn of guessing, the person that sets the secret digit number needs to tell the player that which digit number the player successfully being guessed. 

 

Bull means the number of digits that are successfully being guessed and the digit(s) are in the right digit place. 

Cow means the number of digits that are successfully being guesses but the digit(s) are not in the right digit place. 

For instance, 1 Bulls 2 Cows, it means that you have guessed 3 digits correctly, 1 of them is in the right digit place and 2 of them are in the wrong digit place.

 

Note that

• the secret digits set are not repeated. For example, '1231' is an invalid secret code.
• "0" cannot be in the first digit of the secret code. For example '0145' is an invalid secret code.