How Special Is Your Birthday? (Mathematically Speaking, That Is)

Caitlin Schneider

Sure, your birthday is your important day, but it's not only yours. What are the chances of two people in a group sharing a birthday? It's actually a lot more likely than you think.

In the video above, Joe Hanson from It’s Okay To Be Smart celebrates the program's third birthday by diving into the probability of shared birthdays. How crazy is it that out of 44 presidents, James K. Polk and Warren G. Harding share a November 2 birthday? Not crazy at all: In a group of 44 people, there’s a 93 percent chance that two of them will have been born on the same day.

That stat seems pretty remarkable, but as Hanson says, it’s because “our brains are bad at figuring out the power of chance.” Check out the video for more dizzying data on the probability of shared birthdays, and for a good explanation of why the numbers work out that way. Plus, the reason why the frequency of Facebook birthdays hits a milestone at about the 2153 friend mark.

Banner image via YouTube.