The birthday paradox. If you have 23 people, there's a 50% chance they share a birthday

birthday_paradox.py

from collections import Counter
from random import randrange

results = []

# Run this 10k times
for _ in range(0, 10000):
    # Give me 23 random birth dates given 365 days in a year
    birthdays = [randrange(365) for _ in range(23)]
    # Check for any overlap
    results.append(len(birthdays) != len(set(birthdays)))

# There's over a 50% chance of an overlap when there are 23 people
print(Counter(results))