Still neck division

[[PETA] Doodat]

Pretty sure it's about probabilities:
Need to find the percentage of no people have birthdays together (this is continuing to assume that no two people have the same birthday)
For 1 person, there is 365/365
For 2 people, I would say 364/365 to keep it simple, although the fraction is much weirder than that due to leap years.
3 people: 364/365 * 363/365
4 people: 364/365 * 363/365 * 362/365
5 people: 364/365 * ... * 361/365
And so on.
Even for 10 people: already ~12% chance that 2 people will have the same birthday. (because ~88% chance that they will not have the same birthday)