Dr. Number

Daily challenge, live duels, global rankings. Crack the hidden number in as few guesses as you can, then take on a friend head-to-head.

Dr. Number is a number-deduction puzzle — a code-breaking brain game reimagined with daily challenges, real-time duels, and global rankings.

The game goes by many names: Bulls and Cows, Cows and Bulls, Hit and Blow, Number Baseball, 1A2B. The rules never change — crack the hidden number.

HOW TO PLAY Guess the secret code. Each guess tells you how many digits are exactly right (right digit, right spot) and how many are close (right digit, wrong spot). Use logic to crack the code in as few tries as possible.

THREE WAYS TO PLAY • Daily Challenge — Everyone in the world solves the same puzzle each day. Build your streak and share your results. • Single Play — Choose 3 or 4-digit codes, track your best records, and use pencil marks to narrow down the possibilities. • Versus — Jump into a quick match, or challenge a friend directly. Both players set a secret code and take turns guessing — first to crack it wins. Climb the ranked leaderboard.

FEATURES • Global daily rankings and versus leaderboards (Elo-based) • Invite friends with a code or QR link for private matches • Pencil marks (memo) to track possible digits like a notebook • Unlockable color themes and avatars • 10 languages supported

YOU WILL LIKE THIS IF YOU ENJOY • Number guessing games and logic puzzles • Brain games and mental workouts, the way sudoku is • Quick single rounds that fit into a short break • Head-to-head puzzle duels against friends

No reading required — the rules click in seconds, and the logic keeps you coming back.

Start Dr. Number today and climb the Bulls and Cows leaderboard!