Crack the 4-digit code
Type 4 unique digits, then press Enter
No guesses yet — start playing!
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1A2B — also known as Bulls and Cows — is a classic number deduction game that has been played with pen and paper for decades. One player secretly picks a 4-digit number where all digits are unique, and the other player tries to crack the code through a series of logical guesses. Each guess is scored with two clues: A counts digits that are correct and in the right position, while B counts digits that are correct but in the wrong position. The goal is to reach 4A0B — meaning you've cracked the code perfectly — in as few guesses as possible.
Start by typing any 4-digit number using unique digits (no repeats). After each guess, you'll see your A and B score. Use the clues strategically — if you guess 1234 and get 1A2B, you know one digit is perfectly placed and two others exist in the secret number but are in the wrong positions. Eliminate impossible digits, narrow down the positions, and work toward 4A0B. Most players can crack the code within 6 to 7 guesses with good logic. Press R on your keyboard or tap Restart to begin a new game at any time.