About this app
Remember playing this with a pencil in the back of class? Each of you hides a secret number, trading guesses turn by turn — first to crack the other's code wins. That game now lives in your pocket. The rules take 30 seconds: A = right digit, right spot; B = right digit, wrong spot. Use those two clues to crack the secret number in as few guesses as you can. Simple rules, pure deduction, minutes a round. — DAILY CHALLENGE One puzzle a day, the same for everyone worldwide. Build your streak and share your result with friends. — 3 TO 10 DIGITS Start easy with 3 digits or push your limits at 10. From casual to hardcore. — PENCIL & PAPER TOOLS, BUILT IN The best part of 1A2B has always been scribbling notes while you deduce — so we built it in: • Digit marks: one tap crosses out digits you've ruled out, or circles the ones you know are in • Position notes: jot candidate digits for every slot and narrow the answer down step by step • Notes save automatically with each game — leave and pick up your deduction right where you were — AND MORE • Full guess history — see every step of your deduction • Stats and win rate to track your progress • Hand-drawn notebook feel, like deducing on real paper • Fully playable offline — commutes, queues, bedtime Ready? Today's number is waiting.
Latest release
What’s New
Improved user experience.
Audience growth
Ratings growth
Baseline captured. Growth appears after the crawler observes a changed rating count.
Momentum comes from crawler snapshots for the tracked storefront. “Viral growth signal” means unusually fast recent rating gains; it is an indicator, not download data.
Price tracking
Price intelligence
First snapshot captured. The trend line starts after the next crawler price observation.
- First observed Sep 4, 2026 · 5:20 AM Free
Screenshots
