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

On a sheet of paper, the players each write a 4-digit secret number. The digits must be all different. Then, in turn, the players try to guess their opponent's number who gives the number of matches. If the matching digits are in their right positions, they are "bulls", if in different positions, they are "cows". Example:

Secret number: 4271

Opponent's try: 1234

Answer: 1 bull and 2 cows. (The bull is "2", the cows are "4" and "1".)

The first player to reveal the other's secret number wins the game