Bulls and Cows (Number Guessing)

A number guessing game, also called Bulls and Cows or number baseball, in which you find a hidden number from bull and cow clues. You can guess the computer's number, let the computer guess yours, or play against another person on one device.

How to use

1. Under "Mode", choose "Guess my number", "Computer guesses" or "Two players".
2. Set the "Number of digits" (3 to 5), "Allow repeated digits" and "Allow 0", then press "New game".
3. Type a number and press "Guess"; each result is added to "Guesses". Mark digits on the "Memo board" to keep track of what you have ruled out.
4. In "Computer guesses", write your number on paper. For each guess, enter the bulls and cows and press "Send answer".

How it works

• A bull (S) is a right digit in the right place, a cow (B) is a right digit in the wrong place, and out means no digit matches.
• The computer guesses a number that still fits all answers and leaves the fewest possibilities in the worst case. If your answers contradict each other, it tells you.
• The current game and the best score for each set of rules are saved in this browser.

Questions and answers

How do you score bulls and cows?

If the secret is 427 and the guess is 724, the 2 is in the right place (1 bull) and the 4 and 7 are in the number but in other places (2 cows).

How many possible numbers are there with 3 digits?

With no repeats and the digits 1 to 9, there are 9 × 8 × 7 = 504 numbers; with 0 allowed, 10 × 9 × 8 = 720. Switch on "Show how many numbers are still possible" to see how many remain after your guesses.

How does the two-player mode work?

Each player hides a number, then you pass the device and take turns guessing. Player 2 always gets the same number of turns as Player 1, and finding both numbers in the same round is a draw.