The hidden code is usually made from distinct digits or symbols. After each guess, the game reports the number of bulls and cows without revealing which symbols produced them. The player uses this information to eliminate possibilities and deduce the secret code. Rules about repeated symbols and code length depend on the particular version and are not specified here.

Begin with guesses that test as many different symbols as possible. Record every guess and its bull-and-cow result, then compare candidate codes against all previous results. Separate exact matches from symbols that are present but misplaced, and avoid repeating a candidate that has already been ruled out. When repeated symbols are allowed, track confirmed counts as well as positions.