Cows And Bulls (Numerical Version), How to Play: Follow the instructions. If you are inputting a number, make sure that the number you put in has only 3 digits and doesn't repeat any digits. For example, "000" is not allowed but "012" is allowed. In the result, C means there is a digit in the used number, but not in the correct spot. B means it is both in the right spot and is the right digit. Each "B" and "C" refer to a digit in the guessed number. The aim of the game is to try to figure out the number the computer used in as few guesses as possible.