Bulls and Cows (1A2B)

🕹️ How to play

1. How do you start a game of Bulls and Cows?: Pick Solo practice to start guessing at once, or Two players to confirm the rules (4 digits, no repeats by default). Each player sets a secret code — tap Random if you can't think of one — and the screen covers itself before the phone is passed.
2. How do you guess?: Type digits on the keypad and press Submit. The result reads like 1A2B: A (bulls) are right digits in the right place, B (cows) are right digits in the wrong place. Use each result to rule digits out until you hit 4A0B.
3. How do two players share one phone?: After each guess, tap Pass to rival. The screen stays covered until the other player taps their name, and no code or notes are ever shown while covered. At the end both codes are revealed and every guess is coloured digit by digit, so nobody can cheat.

📖 Rules & variants

Bulls and Cows rules: the code uses digits 0–9, 4 digits long with no repeats by default, and it may start with 0. After every guess you learn how many digits are right and in place (bulls, A) and how many are in the code but misplaced (cows, B). 4A wins.

Worked example: code 4271, guess 1234. The 2 is in the right place — 1 bull. The 1 and 4 are in the code but misplaced — 2 cows. Result: 1A2B. The 3 isn't in the code. The score says how many, never which.

Scoring with repeated digits: each digit matches only once, bulls first. Code 6622, guess 2666: the second 6 is a bull; one 2 and one more 6 are cows, so the answer is 1A2B — not 1A3B, a common mistake in hand scoring.

Two-player result: if the first player cracks the code, the second player still gets the last guess of that round — crack it too and it's a draw. If the second player cracks it first, they win outright. 30 guesses each without a winner is a draw. Rematches swap who goes first.

Invalid guesses don't cost a turn: too few digits, a repeated digit under no-repeat rules, or a number you already tried are blocked with the reason shown. Copying your rival's guess is fine — you're cracking different codes.

Variants: 3 digits (720 codes), 4 digits (5,040) or 5 digits (30,240), each with optional repeated digits. Solo practice keeps your fewest guesses per variant and rates each win Mastermind, Sharp, Steady or Cracked.

❓ FAQ