Numbun

Frequently Asked Questions

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What is Numbun?

Numbun is a browser-based number guessing game. The goal is to find a hidden number made of unique digits by using feedback after each guess: + means a correct digit in the correct position, and - means a correct digit in the wrong position. Numbun is free, ad-free, privacy-conscious, and designed to work in the browser, including offline play.

Is Numbun the same as Bulls and Cows?

Numbun belongs to the same traditional game family as Bulls and Cows. The shared idea is deductive code-breaking: a secret number or code is hidden, and the player uses partial feedback to eliminate wrong possibilities and find the answer. Numbun uses + / - clues, while Bulls and Cows uses bulls and cows [1], [2].

Is Numbun the same as Mastermind?

Numbun is Mastermind-like, but not identical to classic Mastermind. Mastermind is usually played with colored pegs, while Numbun uses numbers with unique digits. Both belong to the same broader code-breaking and deduction-game tradition [3], [4].

What do the + and - clues mean?

A + means one digit is correct and in the correct position. A - means one digit is part of the secret number but is in the wrong position. The result shows only the totals; it does not say which specific digit produced each + or - clue. For example, if the secret number is 1234 and the guess is 1456, the digit 1 gives + because it is correct and in the right place, while digit 4 gives - because it exists in the secret number but is in the wrong place.

Why are the digits unique?

Numbun uses numbers with non-repeating digits to keep the deduction clean and readable. This rule is also common in several related variants such as Bulls and Cows, 1A2B, AB, and many number-based Mastermind-style games [2], [5].

Is Numbun a luck game or a logic game?

Numbun is mainly a logic and deduction game. Luck may affect the first guess, but strong play depends on using each clue to remove impossible numbers, compare alternatives, and make better next guesses. This is why games in the Mastermind / Bulls and Cows family have been studied in mathematics, computer science, and reasoning research [3], [4], [6], [7].

What skills can Numbun help practice?

Numbun can help players practice deductive reasoning, hypothesis testing, elimination, strategic trial-and-error, attention to feedback, and systematic problem solving. Educational research on related mind games, including the Mastermind-like game PappaLOTTO, reports promising but preliminary evidence for supporting children's strategic and reasoning abilities [8], [9].

Is there academic research about games like Numbun?

Yes. The broader family that includes Bulls and Cows, 1A2B, Mastermind, AB games, MOO, Hit & Blow, and related variants has been studied in several contexts. Some research focuses on education and reasoning skills; other research studies the game as a combinatorial search, algorithmic, or computational complexity problem [3], [4], [6]–[8], [10]–[14].

Has this type of game been used in schools?

Yes. Bottino et al. studied computer mind games at primary school level and included PappaLOTTO, a Mastermind-style game, as one of the tools used to support strategic and reasoning abilities. A Turkish educational resource, Oyunsever İzmir Zekâ Oyunları 1, also includes Sayı Tahmini as a school-oriented reasoning and strategy game [8], [9].

Does Numbun improve intelligence or school grades?

The safest evidence-based answer is that Numbun can support reasoning practice, but it should not be claimed to directly increase intelligence or guarantee better grades. Existing research on related games suggests educational potential, especially for reasoning and strategy, but the direct classroom evidence is still limited and should be described carefully [8], [9].

What are other names for this game around the world?

The same game family appears under many names, including Bulls and Cows, 1A2B, 猜數字, AB game, Hit & Blow, MOO, Number Baseball, Sayı Tahmin Oyunu, Picas y Fijas, Taureaux et Vaches, Bullen und Kühe, Touros e Vacas, Быки и коровы, Numerino, and Numerello. The names differ by region and language, but the core mechanic is the same: find a hidden code using partial feedback [2], [5], [11].

What game modes does Numbun include?

Numbun includes Normal mode, Daily Puzzle, Blind Start, Cold Case, Daily Case, customizable digit length, hints, local statistics, a whiteboard, sharing, and offline support. Cold Case starts with several generated clues and fewer attempts, while Blind Start hides feedback until the chosen number of blind guesses has been entered.

Can I play Numbun offline?

Yes. Numbun is designed as a browser-based game with offline support, so it can continue working after it has loaded, depending on the user's device and browser behavior.

Does Numbun collect personal data?

According to Numbun's privacy page, the site does not collect or store personal visitor data, does not use cookies or similar identifiers, and stores game progress, settings, statistics, and whiteboard notes locally on the user's device. The site uses Plausible Analytics for aggregate, cookie-free analytics.

Is there a best strategy for Numbun?

There are strong strategies, but no single simple rule is best for every situation. A good general strategy is to make guesses that reduce the number of possible secret numbers as much as possible. This idea is related to classic research on Mastermind strategies, including Knuth's well-known five-guess result for the classic Mastermind configuration [3], [12], [13].

Why is Numbun educational?

Numbun is educational because it encourages players to reason from evidence instead of guessing randomly. Each clue forces the player to revise assumptions, eliminate contradictions, and plan the next move. That makes it a compact practice environment for logical reasoning, structured thinking, and problem solving [3], [8], [9].

References

  1. [1]L. Johnston, "MOO or BULLS and COWS," Decuscope, vol. 10, no. 1, p. 29, 1971. Accessed: Jun. 5, 2026. [Online]. Available: https://www.bitsavers.org/pdf/dec/decus/decuscope/Decuscope_Vol10_1971.pdf. Archived: Internet Archive
  2. [2]C.-L. Liu, "數學、資訊科學與數字遊戲," 科學月刊, vol. 32, no. 3. Accessed: Jun. 5, 2026. [Online]. Available: https://www.cs.nccu.edu.tw/~chaolin/papers/science3203.pdf. Archived: Internet Archive
  3. [3]D. E. Knuth, "The Computer as Master Mind," Journal of Recreational Mathematics, vol. 9, no. 1, pp. 1-6, 1976-1977. Accessed: Jun. 5, 2026. [Online]. Available: https://www.cs.uni.edu/~wallingf/teaching/cs3530/resources/knuth-mastermind.pdf. Archived: Internet Archive
  4. [4]J. Stuckman and G.-Q. Zhang, "Mastermind is NP-Complete," arXiv:cs/0512049, 2005. Accessed: Jun. 26, 2026. [Online]. Available: https://arxiv.org/abs/cs/0512049. Archived: Internet Archive
  5. [5]T. Tanaka, "The minimum strategy and the strongest strategy of the number guessing game MOO." Accessed: Jun. 5, 2026. [Online]. Available: https://www.tanaka.ecc.u-tokyo.ac.jp/ktanaka/moo/moo-en.html. Archived: Internet Archive
  6. [6]G. Viglietta, "Hardness of Mastermind," arXiv:1111.6922, 2011. Accessed: Jun. 26, 2026. [Online]. Available: https://arxiv.org/abs/1111.6922. Archived: Internet Archive
  7. [7]J. Golde, P. Haller, F. Barth, and A. Akbik, "MastermindEval: A Simple But Scalable Reasoning Benchmark," arXiv:2503.05891, 2025. Accessed: Jun. 26, 2026. [Online]. Available: https://arxiv.org/abs/2503.05891. Archived: Internet Archive
  8. [8]R. M. Bottino, L. Ferlino, M. Ott, and M. Tavella, "Developing strategic and reasoning abilities with computer games at primary school level," Computers & Education, vol. 49, no. 4, pp. 1272-1286, Dec. 2007, doi: 10.1016/j.compedu.2006.02.003.
  9. [9]İzmir İl Millî Eğitim Müdürlüğü, Oyunsever İzmir Zekâ Oyunları 1, İzmir, Türkiye, 2025. Accessed: Jun. 26, 2026. [Online]. Available: https://izmir.meb.gov.tr/izop/oyunseverizmirzekaoyunlari1.pdf. Archived: Internet Archive
  10. [10]J. M. Grochow, "MOO in Multics," Software: Practice and Experience, vol. 2, pp. 303-308, 1972. Accessed: Jun. 5, 2026. [Online]. Available: https://multicians.org/moo-in-multics-1972.pdf. Archived: Internet Archive
  11. [11]Multicians contributors, "moo," Multics Glossary -M-. Accessed: Jun. 5, 2026. [Online]. Available: https://multicians.org/mgm.html. Archived: Internet Archive
  12. [12]G. Jäger and M. Peczarski, "The Worst Case Number of Questions in Generalized AB Game with and without White-peg Answers," arXiv:1306.1713, 2013. Accessed: Jun. 26, 2026. [Online]. Available: https://arxiv.org/abs/1306.1713. Archived: Internet Archive
  13. [13]M. El Ouali, C. Glazik, V. Sauerland, and A. Srivastav, "On the Query Complexity of Black-Peg AB-Mastermind," arXiv:1611.05907, 2016. Accessed: Jun. 26, 2026. [Online]. Available: https://arxiv.org/abs/1611.05907. Archived: Internet Archive
  14. [14]A. Martinsson and P. Su, "Mastermind with a Linear Number of Queries," arXiv:2011.05921, 2020. Accessed: Jun. 26, 2026. [Online]. Available: https://arxiv.org/abs/2011.05921. Archived: Internet Archive