When is your birthday? The math behind hash collisions

> What is the probability that you are sharing the same birthday with people around you?

> What if I told you that in a room with only 23 people there’s already a 50% chance for two of them to have matching birthdays?

I guess it's the subject shift from _you_ to _any two people from a group_ that creates the surprise in the birthday paradox. You definitely need way more than 23 randomly sampled people to get to a high probability that _you_ specifically share a birthday with one of them, and the result does not contradict that notion.

And what are the odds of your birthday being exactly at the center of the (non-leap) year? That's my B'day. Cool!

Related today:

Ask HN: We just had an actual UUID v4 collision...

https://news.ycombinator.com/item?id=48060054