🎉 Shared birthday (23 people) vs 🪙 10 heads in a row
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You're 512.0× more likely to share a birthday in a group of 23
than to flip heads 10 times in a row
Periods differ: Shared birthday (23 people) is framed as group of 23 people, while 10 heads in a row is per sequence of 10 fair flips. The multiplier is a raw ratio of the 1-in-X figures — not a normalized lifetime risk. Compare cautiously.
Shared birthday (23 people)
~50.7% (about 1 in 2)
group of 23 people
10 heads in a row
1 in 1,024
per sequence of 10 fair flips
How we calculated this
Each figure is “1 in X.” The larger X is the rarer event. Dividing that number by the more common one gives the multiplier: you're 512.0× more likely to share a birthday in a group of 23. When the periods differ, this is a raw ratio of those figures, not a lifetime-normalized risk.
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You're 512.0× more likely to share a birthday in a group of 23 (~50.7% (about 1 in 2), group of 23 people) than to flip heads 10 times in a row (1 in 1,024, per sequence of 10 fair flips). ⚠️ Periods differ (group of 23 people vs per sequence of 10 fair flips) — compare cautiously. — How Likely Is That? https://www.howlikelyisthat.com/compare/birthday-paradox-odds-vs-odds-of-10-coin-flips-in-a-row
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