Surreal Numbers Lab
A visual, step-by-step sandbox for high school and undergraduate math students that builds up Conway's surreal numbers from simple games, so the abstract construction finally feels intuitive.
Curious high schoolers, math undergraduates, and self-taught math hobbyists
- Build surreal numbers by hand: pick a Left and Right option and watch the birth-day of the new number appear
- Visualize the number line growing to show how 0, 1, 1/2, and beyond are born from games
- Mini-challenges that test understanding of 'simplest number not yet born' at each step
- Teacher mode: assignable puzzles with auto-graded answers and a class progress board
The Lean 4 library and active research into surreal-number field structure have refreshed interest in Conway's construction, but most students only ever meet it as a hard-to-visualize definition.
Surreal numbers are a niche topic taught in graduate seminars (e.g., UC Davis) rather than mainstream curricula; HN discussion drew modest interest and no high-school standard addresses it.Surreal Number Seminar Syllabus ↗Surreal Numbers - An Introduction (2019) [pdf] | Hacker News ↗
A free interactive surreal-number tree visualization already exists at iris.joshua-becker.com and a Wolfram Cloud notebook exists, so the 'visual sandbox' angle has prior art rather than being wide open.Conway's Surreal Numbers ↗Generating the Surreal Numbers ↗
Audience is tiny (curious undergrads/hobbyists) with abundant free alternatives (Knuth's book, Wikipedia, Becker's lab, Wolfram notebook); a paid surreal-number app would struggle to justify pricing near Brilliant's $10.99/mo tier.Brilliant Pricing 2026 ↗Surreal number - Wikipedia ↗
Conway's construction is a fixed mathematical object so content doesn't decay, but the learner audience is small and not growing; Lean 4 library work adds sporadic academic attention but not mainstream demand.GitHub - vihdzp/combinatorial-games ↗
Visual day-by-day construction is implementable (Becker already shipped a working version), but encoding the simplicity rule, ordering, and arithmetic correctly with educational scaffolding is non-trivial engineering.Conway's Surreal Numbers ↗