Observed arrival · 2026-11-02
By the Billion: probability you can replay
A collection of probability answers backed by large simulations, with chunks readers can replay in their browser and exact calculations where available.
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✦Pretty
●Pro
◎Niche
◉Human
⚑Risk
ƒJS
- For
- Curious readers checking probability claims
- Worth noticing
- The page reports 769,000 replayable chunks and a second-language program that checks random chunks from new batches.
Field notes
For the Secret Santa example, the page explains the setup as everyone drawing one name from a hat with no do-overs, then compares simulation results across group sizes. It notes that the probability of at least one self-draw settles near 63.2% from about six people onward, alongside exact answers derived from counting shuffles with no self-draws. The site reports 88.6 CPU-hours for its accumulated runs.
Observed signals
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Editorial observations of this landing page, not a rating.
○OpenPublic substance visible
✦PrettyNotable craft visible
●ProPolished or operationally mature
◎NicheUnusually specific use
One card from the complete issue