this post was submitted on 21 Sep 2026
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In probability theory, the birthday problem asks for the probability that, in a set of n randomly chosen people, at least two will share the same birthday. The birthday paradox is the counterintuitive fact that only 23 people are needed for that probability to exceed 50%.

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[–] bizarroland@lemmy.world 7 points 2 weeks ago* (last edited 2 weeks ago) (1 children)

I work in a company of about 80 people, and there are at least three sets of people with matching birthdates.

I say at least because I don't know everyone's birth date.

[–] HubertManne@piefed.social 5 points 2 weeks ago

wow. the only reason I know many family members birthdays is because its in my calendar.

[–] Pappabosley@lemmy.world 1 points 2 weeks ago (2 children)

I find that interesting, in my family unit of my 2 parents, 4 siblings and our 5 partners, we don't even have 2 birthdays in the same month - which just makes it sound even more counter-intuitive to me, not that I'm disbelieving it, just relating it to my personal experience. . Once we go to the next generation, with my children, nieces and nephews, that adds another 12 people and the closest we got was 3 days apart.

[–] dantheclamman@lemmy.world 2 points 2 weeks ago (1 children)

My dad and his two siblings had the same birthday. It is a weird bit of trivia and I never got to ask my grandparents what the heck was going on with that!

[–] Pappabosley@lemmy.world 1 points 2 weeks ago

Clearly they had one day a year scheduled for sex

[–] psilotop@lemmy.world 1 points 2 weeks ago

What made me understand this was realizing that it meant any two people. The first time I heard this I was thinking that if I was in a group of 70 or 80 people, there was almost a 100% chance of someone having the same birthday as me. But it's not comparing to an individual, it's comparing all of the pairs. I hope that makes sense