Mathematical explanation here

1) Equifax Version

In a room of 23 people, there is a 99% chance that at least one person has had their birthdate information stolen in an Equifax data breach.

2) Suit Version

In a room of 23 people wearing their birthday suits, there is a 52% chance they are at Burning Man.

3) Cat GIF Version

In a room of 23 people, there is a 68% chance that at least one person has sent or received a birthday GIF involving cats.

4) Electoral Version

In a room of 23 people that includes Donald Trump, it is one person’s birthday. Nate Silver, upon studying the room, projects a 29% chance that it is Trump’s birthday. The New York Times estimates a 15% chance that it is Trump’s birthday. Huffington Post claims there is a mere 2% chance that it is Trump’s birthday. It turns out to be Trump’s birthday.

5) Retail Version

In a room of 23 people, each person can get 15% off at American Eagle Outfitters on a single purchase during their birthday month (certain restrictions may apply).

6) Climate Version

In a room of 23 people whose first birthday was after 1976, 0% of them has experienced a year when Earth’s annual average surface temperature was cooler than 57°F (13.9°C).

7) Doom Version

If you are in a room of 23 people and everyone shares the same birthday, there is a 75% chance that you have been rounded up by a brutally efficient authoritarian regime and face impending doom.

8) Half-Birthday Version

In a room of 23 people, there is a 50% chance that at least two people have the same half-birthday.

9) Medical Version